Cloverfield Pro's and Con's
PRO
-The hand-camera gave the film a tense feel, that is, when you didn't feel like throwing up
-The sense of scale when they had shots from above the monster were amazing
-There were some really cool moments here and there

CON
-THAT'S the monster? It looks like a bat mated with a praying mantis then its mother did heroin while pregnant. It's just that bad. The mutant-whale designs were much cooler and would have fit the whole "it came from the ocean" feel a bit better.
-After Elena, or whatever the hell her name was, blows up in a bloody spectacle, the whole movie kind of devolves. The plot doesn't really go anywhere, and the ending is just shit-tastic
-The "witness-cam" thing with the cam-corder gets really annoying and a bit disorienting. At one point I felt like throwing up.

Basically, this movie is one of the biggest disappointments of the past year. It's not bad, but it's not good, either. I know some people are hailing it as a "masterpiece of cinematography," but those people are probably high on something. The whole plot consists of 3 segments:
1. Rob's going away-party, where it sets up all the characters, and when the monster attacks.
2. Finding Beth. Rob's girlfriend is injured and stuck in her apartment, and they have to go rescue her. This part contains a really cool scene where a girl explodes due to being bit by this venomous bug thing.
3. Get to the evac point. They have to somehow get to the evac point without being utterly raped by Mr. Giant Retarded Batmantis and all of the little beasties swarming the city.
That's it. It's not that the plot itself is bad, it just feels rushed. And that wouldn't be so bad if the ending wasn't a complete goatfudge that leaves no resolution of any kind.

Anyway, if you're feeling adventurous, I say go see it. Just don't go in with high expectations, like I did.
Final rating: (and that's being fairly generous)