Ghost Reveries hasn't been out long enough for me to truly give it a ranking. But, at this moment in time, it is my second favorite Opeth album, with Blackwater Park (my #1 favorite album by any band) being my favorite.
What GR has going for it:
Ghost of Perdition has eclipsed The Drapery Falls as my favorite Opeth song. In fact, GoP in my favorite song, period.
The album flows quite well.
Well produced, as I admittedly have enjoyed Opeth's production from BWP forward. My ears tend to like well produced sound better.
What GR doesn't have going for it:
[empty list]
I don't have the negativity towards The Grand Conjuration as many others have. In fact, it's probably my 2nd or 3rd favorite song off the album.
I do not analyze music well, thus, it's hard for me to discuss the merits of the album technically. I feel it is as genious as any other Opeth album. I don't feel they've "sold out", nor do I feel they've entirely changed their direction. They just continue to grow over time.
That being said, as with all Opeth albums, time will tell. Even as an experienced Opeth listener, each album has taken time for me to digest and understand, and GR is no different.