1. Believe the hype. For those who cynically predicted this would be a big cinematic con job and the movie would never fully reveal the danger (ala The Blair Witch Project), rest assured that it delivers the goods.
2. The subway tunnel sequence is among the scariest, most intense ever put on film. It ranks right up there. This is a very hardcore PG-13.
3. The first 20 minutes are a little dull, perhaps, but you have to set up the characters so you'll care about what happens to them later on. Some critics have snarked that the characters are all cardboard pretty faces, full of callow angst like those on J.J. Abrams' first TV hit "Felicity." There's some validity to that, but keep in mind that "Felicity" was a fairly successful show.
4. The lead character's "Felicity"-ish quest to risk his life to go find the girl he stupidly rejected before the attack began gives the movie what little emotion it has. And it's just enough. We're not here to see dynamic character arcs and subtle internal struggles. We're here to get scared and see things we've never seen before.
5. The conceit with the first-person camcorder works well, especially the way the filmmakers play with the idea that this attack footage has been taped over older footage. The clever juxtaposition between the two timelines is more poignant than you'd expect.
6. Note to self: you don't want to hear the sirens signaling the start of a Hammer-Down.
7. This is a movie packed full of amazing visual effects, made all the more impressive given the shaky handheld camerawork. It's not often that the Cheese Fry is left wondering "how the hell did they do that?" Happens many times in this film.
8. If there's a worry, it's the way Cloverfield so vividly evokes 9/11, especially in the first half hour as a cloud of debris floods the streets of Manhattan as buildings come down and onlookers flee in panic. In what's otherwise a traditional popcorn sort of movie, that imagery feels too realistic, too tragic. The film turns a modern-day horror into entertainment, which is a little queasy.
9. An ingenious idea executed at a high level: a B-movie monster flick told the from the POV of the frightened civilians caught in the middle, not the brilliant monster expert or the dour Pentagon general or the charismatic American president.
10. Go see it.