I think what many people fail to realize is that Opeth, no matter what sound they do, have usually been about making sure that each album has its own trademarks, styles, tempos, genres, and songwriting methods.
Still Life - Mixtures of gore-grind inspired gutterals, 80's power-ballad guitar harmonics, a medieval aura alike to Shakespearean works such as The Moor, a bit of smooth jazz on the ballads, and a somewhat "jarring" transitional style heard on My Arms, Your Hears, and then Ghost Reveries, and finally, blazing twin-guitar choruses and solos.
Blackwater Park - A blend of slightly blacker tones than Still Life, as in slight black metal tinges, mixed with heavier bass layers, and amped up production values in terms of almost pop-ish and progressive vocal effects, with pianos and more focus on acoustic numbers, paired with an inventive, 80's heavy-jazz-death-metal (Bleak, Funeral Portrait, and the middle death section of Blackwater Park) that also incorporates swings and tempos of politcal-nu-metal such as early Deftones and Rage Against The Machine (listen to those bands' early albums and see if you don't hear that type of tempo and swing!).
Damnation - A divulge of smooth jazz and acoustic hybrids, harking back to immediate post-war Great Britain landscapes in terms of sound, and some focus on farmhouse or village textures as well, incorporating some of Opeth's most mainstream choruses and groovy tempos, and incorporating influences of talk-talk and spoken word poetry.
Deliverance - An extreme focus on a blackened-death sound, signalized by a much more direct and brutal focus on blastbeats, layered screams, and bulgening tones, also containing a few Metallica-esque passages and some inspirations of Blackwater Park, with touches of some of Opeth's most surreal and beautiful-noise passages.
Ghost Reveries - A revisit to the groove and old-school metal inspired layering that made Still Life so much fun, incorporating once again the elements of Satanism and Occult, however yet layered with such an tremendous psychedelic influence with newfound keys and organs, focusing on abrupt and ADHD-esque transitions and tempos that reflect the drugged-out mentality of the album's mentally diseased main character (a BIG point that MANY PEOPLE don't seem to GET! The album is about a man who practically dabbles in witchcraft, kills his mom for it, then realizes witchcraft isn't real, and that he's just insane!). Also strown about are psychedelic and blues ballads, a first for Opeth.
Watershed - A slightly less complex follow-up to Ghost Reveries, focusing on a strong Sleepy Hollow-type sound, with pilgrim-esque numbers and mysterious songs that spell out old-tyme stories and moods, also containing a few random mega-hits such as the 80's power-ballad and the zany, nintendo-metal romp. I think most fans can admit that this is really the only album where Opeth starts to show "true" weakness in the form of an unfinished portrait feel.
Heritage - A 70's progressive album devoid of growls or any of the shiny, perfectionist production that had both made all previous Opeth albums so enjoyed by young adults and perfectionist musicians alike, an album that generates a trudgy, cloudy, stoner-esque portrait, though with mostly down-tempo and almost depressive songs, with a few "classic" 80's rock/blues songs in the mix such as Face In The Snow and Slither. I think many fans can agree that this is the "low point" for Opeth, with the general sense that the album doesn't paint the full picture the band seems to want.
Storm Corrosion - A beautiful album taking many marks from the perfectionist production of Damnation, but with styles that harken to dark, or alternatively, very beautiful, village-esque stories and landscapes, much like works of Tim Burton, J.R.R. Tolkien, and other Great Britain, Appalacian Mountain, and Swede tones that mix with vintage, 1940's vynyl-record-sounding samples and sound effects. I think many fans, despite what they may feel about the "fun" of the album, can agree that this is a much more polished, perfectionist, professional, and "complete" album than Heritage.
I personally just don't see where Opeth has fallen into any real dip in talent before Heritage. Ghost Reveries is my favorite Opeth album (it has what I love about each 4 albums before it) and I personally LOVE the psychezophrenic vibe because it relates so much to the insane character in the plot, much like Still Life's vibe related to the character's slow, meanacing, brutal strength, and his bloody end. Ghost Reveries is also plain fun, snappy, stompy, groovy, cool, and downright an insanely fun album, moreso than really any Opeth work, though Blackwater Park and Still Life come close. I also adore Damnation (it's one of my favorite albums on earth) and with Deliverance, well, who could not like it? It's not Opeth's most "impacting" but the songs are downright timeless - it has a tremendous personality. And even Watershed, who couldn't love Burden, Porcelain Heart, Coil, and Lotus Eater?
And, well, Heritage - some songs are really good - Slither, Folklore, Lines In My Hand, Face In the Snow.... the rest are quite dull and drab (and not even in a catchy way, like Storm Corrosion or Damnation is), but it really has to be Opeth's worst "full" release. It's like how Damnation has "Ending Credits", sort of a filler track. Heritage has like... 9 filler tracks....
Another thing though, with Ghost Reveries, yes, I believe some parts of the album are meant to sound pshysophrenic much like Still Life sort of did, as the two are about revengeful characters who go sort of nuts and murder people. But Ghost Reveries really only does this on Grand Conjuration, which really is a brilliant song when you finally "get it". The rest of the album, however, is brilliant in the transitions. Ghost Of Perdition, for example, layers every section into the next, either through acoustics, harmonies, or bass, however, you really have to use a good sound system to hear it. You'll hear previous sections' acoustic and bass parts riding to several future passages for minutes on end, yet, to an unfocused ear, one may not hear. This song does it a bit more subtly than many Opeth songs, but a lot more geniusly, if you truly pay attention. The song is absolutely one of Opeth's finest transitional songs, and layers itself better than even a majority of the songs on Blackwater Park or Still Life.
And then, Ghost Reveries has the blues, poetry-ballad, Hours Of Wealth, which is downright a masterpiece, and Isolation Years, which is a great little Damnation clone. Atonement is a one-of-a-kind, an essential song that put Opeth right into the stoner-hookah genre (it's seriously like sitting in a coversation with the Catipillar on Alice And Wonderland, it's like listening to Steven Wilson's Tarquin Tapes!), and the rest of the songs are really darn catchy and worthy in all their own fantastic sections. I don't see how for the life of me that the album is any less than the ones before it. Fantastic, perfectionist production (it sounds a bit "warmer", like Still Life, but so ultra-crisp and layered - I can hear the vibrations of the drum tops bouncing, that's how good it is), fantastic songwriting, so much complexity, brutality, and fun vibes, and the addition of keys was the best thing Opeth ever done. It transformed them without taking one positive thing away.
That isn't what Heritage did though. Heritage stripped everything from them I ever liked. Damnation and Storm Corrosion did no such thing. Damnation is not any different of an album than Ghost Reveries. The level of talent sounds the same to my ears. I hear no different band. But with Heritage, to my ears, it sounds like a cover band in a garage somewhere. There wasn't one part on it that sounded like the "true" Mikael Akerfeldt. Closest moments were Face In The Snow and the beginning of Folklore. And even then, it sounded more like a bandmate trying to copy Mike's original style. It was just shallow to my ears, it sounded flimsy, it sounded weak, it sounded dull... The other songs sounded like rip-offs of someone wanting to mix a bit of Opeth with almost a nu-metal-esque simplicity, almost as if Sepultura or Korn did a progressive album (actually Korn's Untitled is wayyyyyyyyyyyy better at the "Heritage" sound than Heritage, the two album's are extraordinarily alike. For example, The Devil's Orchard is downright a goofy song. I don't care what anyone says. It sounds like it was written by a 40-year-old man wishing he was 15 but somehow, at 15, has an infatuation with the 70's while wanting to have angsty lyrics.
I mean, whoever thought Opeth would have a line saying "God is dead". That's plain childish. It could have been a growled, brutal, death section and my opinion wouldn't change. That whole Opeth-spoof band that came out to mock the release of Heritage with those 80's rock songs was actually a lot better than Heritage, hate to say it. That band simply had energy, at least.
I know it's contradictory that I said that each Opeth album has it's own personality, and really, I believe each before Heritage did, including Storm Corrosion, but I simply don't agree with Heritage at all. I could have adjusted to the horrible, muddy, sloppy production, the unnatural drums, and the lack of complexity, but the songs were plain mopey and badly written. I don't even care about transitions or complexity or none of that. At it's simplest, music should simply be effective, at whatever genre or style it is, and I only got an "effective" feel from just a few songs on Heritage. The rest, to me, sound like cheap, bland, almost telephone-elevator-like music, and not the good ol' Steven Wilson kind. There's a huge difference from good-but-boring music, and bland-cheap-boring music. Heritage just wasn't good to my ears, in any single way. I really just can't listen to it.
For example, I do dislike the majority of 80's music in terms of songwriting as well. The sounds are plain cool, but I believe a lot of bands back then suffered because even the most experimental of them had songwriters come in and try to write songs for them, or that each song on the album was written by seperate band members who'd die every other day and not get to write another. Pink Floyd is a great example - I don't think they have a quality standard about the music because virtually every song is written by a different person. Opeth excelled because Mike was always writing, every single time, and he's a genius. But Heritage sounded just like something in the 70's or 80's, and was every bit as weak and shallow standard.
Even the most progressive of those old school bands really never did "break free" of having a "highlight or single" song on the album, and that's what I hated about music from those times periods. Opeth never did focus on "singles" or "highlights", at least, not until Watershed IMO, and not since before Still Life (My Arms, Your Hears really focused on Demon Of The Fall in terms of better production and songwriting standard, setting it up to be a "single" IMO). Heritage was like that IMO. It seemed like a few songs were meant to be singles, rather poor ones at that, and the rest were plain bland and completely unfocused.
Just about the only merit I believe the album will ever have, is much like myself digging into old 70's albums, even if not good, just to explore the sounds heard back then, that Heritage, 30 years from now, may be of some interest to kids looking to explore the zany things that Opeth put out. However, most Opeth albums are such classics that I believe albums like Ghost Reveries and Blackwater Park will be albums that people enjoy for quite a few more decades to come. People still love the song Brick On The Wall. I think people will still authentically love such good songs as The Drapery Falls.
However, to me, at best, Heritage is not an authentic love. It's, at the very best, and exploration of all the sounds and negatives associated with 70's acts, in direct form, and even yet without much needed vynil crackles and cassette-tape organic production, something that I would have actually enjoyed hearing. Heritage even fails at sounding 70's. The Beatles, Jethro Tull, ect ect, that stuff sounds 70's, mainly because of the cassette-tape production styles. Heritage is very obviously a 2000's effort, it actually sounds digital. But badly. To me, it was like no amount of Opeth's vision was truly captured, because I believe if Mike had his way with this album, it'd have been recorded on cassette tape technology, at the very least. That'd have made it interesting for me, if nothing else.