I was surprised no one made a thread for them yet. They recently released their new album New Moon earlier this month. I'd say that their new album and BTBAM's new album are the best two albums of the year IMO.
I had never really heard of Swallow the sun except that Wintersun's Kai Hahto was going to be their drummer. The song you posted was pretty good however and I might have to check out more.
I think they were kind of unknown before they realeased "Hope", which really brought them attention from doom-metal as well as other metal fans.
I've really listened to them a little bit longer, tho I'm not a really big doom-metal fan. I just love them, they've got such a heavy and dark atmosphere in their music. Haven't got around to listen to their latest, should get that done during this week I guess.
I have to say, even though I'm a huge doom fan, I don't really care for this band. I'm not really sure what it is about them that I don't like.