I like this Damnation review.

Protected Witness

Magickal Theatre 33
Sep 27, 2002
AMG said:
Released in 2003, Damnation is easily the most radical departure of Opeth's career. The companion piece to the previous year's Deliverance set, to which it was originally inextricably married (before record company marketing men got their dirty little hands on them), the album is the first to explore the group's non-heavy metal-based songwriting both at length and exclusively. Since all of Opeth's previous outings were specifically conceived for the express purpose of contrasting heavy and light, violent and delicate, black and white, such a uniform presentation would already be surprising enough, but perhaps even more astounding is the realization that Damnation can't even be termed a heavy metal album. This is because, except for very brief moments in the excellent "Closure," not a distorted power guitar chord, not a pounding bass drum, not a growled death vocal is to be found here -- only mellow, melancholy, deeply reflective numbers boasting melodic electric and acoustic guitars, the odd bit of piano and Mellotron (performed by the producer, Porcupine Tree's Steve Wilson), and background string arrangements. Rather, alluringly mournful tracks like "Windowpane," "Death Whispered a Lullaby," "Hope Leaves," and "Ending Credits" are at once complex and supple. Relatively of short length by Opeth standards, they often resemble the short musical interludes separating the band's prevalent explosions of black metal fury and progressive rock excursions. Laid out in unnaturally fluid sequence here, these songs obviously fail to provide the striking, surprise-filled experience that longtime Opeth fans have grown accustomed to, but once the novelty sinks in, those fans will easily come to enjoy and recognize Damnation for the finely executed if unique chapter it represents. In fact, even traditional rock fans with no interest in heavy metal whatsoever are likely to appreciate Damnation for its beautifully assembled, reliably high-caliber songwriting -- it's that good. As for devout metalheads seeking their first taste of Opeth's usual, furiously metallic onslaught, they should start with the aforementioned Deliverance or perhaps 2000's Blackwater Park in order to get a more accurate glimpse of the Opeth they've been reading about. Ideally, however, open-minded listeners will sample both Deliverance and Damnation in the manner intended in the first place: together, as dissimilar halves comprising an astoundingly inspired whole. ~ Ed Rivadavia, All Music Guide

I played damnation for a very conservative female friend of fine who is a great singer (currently wasted in a cover band) and believe it or not she got some mellow Sting vibe from it. Go figure.
Great review by the way.
The more mainstream reviwers have all tended to laud this album unsuprisingly due to the lack of that obvious missing ingredient. No matter how you justify growls to non-metal listeners they are never going to get it.
It's a good review, of course, but it's interesting to note that it's the first time since MORNINGRISE that All Music Guide gave one of their albums less then four and a half stars (they gave DAMNATION a solid four). I guess there ARE critics out there who can appreciate good music when they hear it! :)