Cloverfield is smart, for a PG-13er. Blair Witch sold the sizzle, not the steak. Cloverfield got some sizzle and some steak.
The one-shaky-camera approach obviously is a budget saver, although it may cause problems for anyone prone to motion sickness. Will this film actually cause someone to have a seizure? It's a definite possibility. Some theaters have reportedly warned their patrons that the film may induce motion sickness!
Aside from the low-rent camera work, the film uses unknown actors. There are a variety of set pieces in "canned" locations: a party in an apartment, a journey through subway tunnels, searching in a badly listing high-rise. The high-rise scene is inventive, reminiscent of the upside-down sinking ship in The Posideon Adventure.
They saved their money so you could have a bit of CGI, but even that is doled out in brief snippets. You don't really see the monster a whole lot, but that's OK. The simple plot of a group of friends searching for another friend is delivered with such rapid pace and real urgency that the monster is really a bit player. Cloverfield definitely is more of a disaster movie than a monster movie. Since it's not about terrorism, it can't be accused of direct 9-11-sploitation, but scenes of Manhattan destruction certainly do evoke familiar 9-11 images.
The fact that our cameraman/character is so annoying also is a simple way to lend some dramatic tension, as you can't help wondering what, if anything, will make him finally stop filming his friends in the midst of a calamity.
The casting is also smart. Talented but relatively unknown leads. Lizzy Caplan steals the show as Marlena Diamond. She can look forward to decades of signing stuff at Sci-Fi conventions just for this role. But I think she'll be pretty busy acting for the foreseeable future. Michael Stahl-David looks like a movie star and turns in a good performance as the male lead. T.J. Miller is extremely annoying as cameraman/best friend Hud, and that's what he was supposed to do, right? His largely off-camera performance really holds this film together. Caplan and Miller get the best lines and run with them.
The PG-13 Cloverfield is definitely in line with the current media trend of objectifying the young wealthy, as our early-twenties hero lives in a unusually spacious Mahanttan apartment (condo?), and his damsel-in-distress abodes in a fancy high-rise. Our Prince must save his Princess, after all.
Cloverfield is an entertaining box office hit that I enjoyed. That doesn't happen too often. Can you say sequel? It's already in the works ...