It's was, in a nutshell, a semi-campy/cheesy horror-comedy. It's kind of a difficult, for lack of a better way of phrasing this, genre to pull off. It wasn't perfect, but it wasn't awful either. I'm a fan of Diablo Cody and not just because she won an Oscar for Best Screenplay. I've read one of her book before, Candy Girl, I think it was called. It was funny and had cute little one-liners and her trademark Cody Slang. Even reading interviews given by her, she's funny. She's talented, even if she didn't fully shine through with her sophomore screenplay.
I'm not Megan Fox's biggest fan either, but I think she did the very best she could (which is pretty mediocre) as the bitchiest succubus in Devil's Kettle. I think being a douchebag is the only thing she really knows how to do, since according to rampant rumors, that's exactly what she is.
Anyway, aside from bashing everybody's favorite blue-eyed brat, the studio really only used Megan Fox to sell the film. Despite her starring role in the films trailer, she really wasn't the main character in the film. Amanda Seyfried (aka Needy Lesnicky), was the heroine of the story. She pulled off the nerdy, less attractive friend quite well (even though I think she's beautiful) but she ultimately kicks ass in the end.
Another thing that made me feel slightly uneasy aside from Fox's mediocre acting was the fact that Adam Brody was cast as a killer who's in cahoots with Satan. What wasn't surprising, however, was the fact that he was the lead (lip synching) singer of an indie rock band (Seth Cohen would be proud, seeing as Brody was practically an indie rock king as Cohen on The O.C.).
When Jennifer flashes back and explains her murder to Needy, we see Nikolai (Brody) and the rest of his indie cohorts surrounding Jennifer in the woods near a black hole at the bottom of a water fall. Nikolai ends up stabbing Jennifer to death while singing lyrics from that annoying one-hit wonder...the "867-5309" song, because the girl's name in the song is "Jenny". The point of bringing this up was because it just reminded me of the rape scene from A Clockwork Orange; everybody knows what I'm talking about. It's just something you don't forget easily.
I also found that the movie had a pretty decent soundtrack. Some songs stood out for me. Even the Low Shoulder's evil "hope" anthem, "Through the Trees". I was also excited to hear Florence and the Machine on the soundtrack and Silversun Pickups. I am a fan.
So, to wrap this up, Jennifer's Body wasn't the best horror-comedy I've ever seen, but it wasn't the absolute worst either. I think I'd watch it again. I'd really try and quote the movie or something (like I do most movies I've seen), but I'm just not Ellen Page-y enough to pull off the deadpan sarcasm. Oh well!