This in not the album to introduce you to Opeth. From the opening notes, its clear that this is going to be a different direction. And so it is.
Its worth bearing in mind that this album almost makes a pair with preceeding work 'Deliverance'. Deliverance was a very heavy, riff-ridden and scream filled album, and was quite excellent. Its only after listening to Deliverance that you can really appreciate Damnation.
In contrast to Deliverance, this album is mellow and melancholy all the way through. With no screams from the lead singer, and barely a distorted guitar to be heard (save for a touch on Closure), this is Opeth on a new path. To describe its atmosphere, imagine the lighter parts of Deliverance heard on songs such as 'Absent Friends' and 'Fair Judgement' and make them into an album.
This should not be your first Opeth purchase, and the lack of heaviness means this is not typical Opeth. It still works brilliantly, though. The songs are still thoughful and meaningful, and the lyrics still carefully considered. Taken for what it is, it is very impressive and no track is a filler. Certainly not something to mosh to, save this one for a grey sunday. Excellent.