This movie is a fun watch, but mainly because of Ron Perlman. The action is well done and the story is great, but Perlman makes the character of Hellboy (a demon raised by "the good guys") just amazingly human, with a wry sense of humor. You would be hard pressed to find anyone anywhere who could do this character as well as Perlman, let alone better. The physicality seems to have been tailor made to fit Perlman's features and the delivery of the lines is just so understatedly comedic that there are few who could pull it off at all.
Of course, there are a couple times when the special effects are a little weaker than you would hope, but it doesn't detract from the movie as a whole. For instance, in the final battle scene, there are a couple shots where the Hellboy character clearly appears to be GC. But the fight moves so fast that you don't have much time to focus on those shots before something else amazing happens.
See it. Love it.
