Yeah, the score in the credits was phenomenal. I know inserting that into the camera footage would've removed the film from it's handycam thing, but - man! - that stuff would rock in a conventional monster film.
I'm not quite sure what you went in wanting to watch. The film advertised a monster movie filmed on handycam and delivered - in spades. It's definitely not open for repeat viewings or critical analysis (it's not a metaphor for anything, it's not deep or anything).
There are folks that are definitely going to be frustrated with the ending, but I liked the grim finale.
Really, I can't really fault a movie that says, "This is what I am!" and you go to see it on that basis. Why go see Cloverfield when you wanted more than just a monster movie filmed on handycam?
Go see There Will Be Blood instead or something!