You should see his first short film Six Shooter. Really good and cut from the same funny/violent cloth as In Bruges.

I think the latter is a proper cult film - like Withnail or Gregory's Girl it won't register for years yet. I think the reason it's not been raved about is Colin Farrell. The received opinion is he's not supposed to be any good so no "tastemaker" wants to risk being laughed at for suggesting the opposite. It's kind of nice to have one good thing that's a little bit secret, though.