Casting aside, this is not a fancy film. There's not much in the way of flashing effects, nor is the story going to make you contemplate your navel(... Well, actually, some of Needy's dialogue seems to be this in the literal sense). But it's a film that's clearly written by fans of horror movies, for fans of horror movies. Somewhere between a parody and a pastiche, "Jennifer's body" is an amusing story of a libby, her best friend, an immoral rock band, and a demon or two. The characters aren't astounding, but they keep the plot moving, and I find it easy to root for Needy. There's very much a sense of disillusionment as Jennifer's demonic powers take more and more hold of her, and Needy comes to see her former friend for who she really is. While a casual viewer might look at the story as a simple catfight written for people who are into that sort of thing, there is an honest to goodness maturity between the horror tropes and comedy. Not groundbreaking by any means, but endearing all the same.
There are a bunch of delightful nods to various horror films, more than a handful of them being to the Evil Dead franchise. All in all, a film I recommend that any horror or horror/comedy fan check out at least once.