Cloverfield

So for the past few days I have been seeing the Trailer for the movie Cloverfield run, and throughout the whole series of them I still had no idea what the movie is about. It's hard to figure out what genre it is like is it scary or a monster movie or just suspense or sci-fi or whatever. I then asked myself if that is a good advertising tactic for movies at least, to leave a lot of ambiguity so the viewer gains interest. However I have to say I haven't gained much interest though. It has a bit TOO much confusion so I'm not sure if it looks interesting or not. What do you guys think?

Here's a link to the trailer in case you have no idea what I'm talking about: http://www.fandango.com/videos_1_688137/v413038