I've heard The Decemberists compared to Belle & Sebastian, and although I'm sure B&S fans would enjoy this album, I don't think the comparison really does The Decemberists justice.
Belle & Sebastian stick to songs about the ironies and awkwardness of growing up in modern Britain, whereas The Decemberists sing about the fragility and turmoil of life in the 19th Century. The music isn't ironic either, it's sincere, and you can't help but be drawn into their world.
There's certainly a vast number of good, even great, indie pop bands around at the moment (Death Cab for Cutie, the Shins, Neutral Milk Hotel), but I think the Decemberists are in a class of their own, if only because they stick to and enjoy their subject matter so devotedly. I don't think there's a song on the album which doesn't feature the trademark organ.
I highly recommend 'Castaways and Cutouts', their first album, too.