This definitely isn't as palatable as Fight Club, Chuck Palahniuk's other adapted work. I'm gonna say that you either love or hate this movie. I, of course, just mostly liked it. Any emotion too strong either way is way beyond my means apparently.
Everything in the movie is sort of absurd, the smaltzy gets a bit heavy, and the tone swings wildly between depressing and hilarious, but I found myself entertained every step of the way. Which is much better than anything something like Burn After Reading had to offer.
Sam Rockwell is creepy and attractive at the same time, which is pretty hard to pull off if you think about it. His big sidekick Brad William Henke is sort of Seth Rogen's cinematic older brother, back when Seth Rogen was actually funny -- like for a second. As for Kelly Macdonald, some people might cringe over her acting skills but I really dig her weird monotone-ish, perpetually hurt, delivery and find her very capable. But like my friend said after watching the movie, "She's like Kate Winslet. But not."
I think I'm going to go read the book now. Then again, maybe I should pass on that. It might be too much for my virgin eyes/ears. Fox Searchlight had novel promotional swag for the movie, which caused a brief Internet blip a few months back. Additionally, I love The Christian Science Monitor's terse review of the film, which speaks volumes -- a plot point concerning Jesus' foreskin might have turned them off -- plus the reviewer dismisses Fight Club. Blasphemy.