This is a lot more remarkable than you might first suspect. The Internet contains many people who make a point of uncovering every detail of a movie long before it comes out. No-one's entirely sure why someone would dedicate their life to doing this, although I personally suspect it may have something to do with the sodium imbalance caused by eating too much ham.
Consequently, we can conclude that the security the producers erected around the film was intense. For example, according to some rumors, during casting actors reportedly weren't handed actual scripts. They instead read dialog from similarly themed television shows - Murphy Brown I'm guessing.
Given the lack of concrete information about the film, speculation about the true nature of the monster has been rampant on the Internet. Favorite theories currently suggest that it's an alien, or a genetically engineered superweapon, or a Lovecraftian inspired monster from the deep. Following an interview where Abrams stated that he came up with the concept while on a trip to Japan, some have also suggested that the monster may be some sort of Voltron style robot.
I think the Internet may be on the wrong track here. Everything we know suggests this monster is a horrendous object of terror. Voltron wasn't terrifying. It was awe-filling and arousing. No, if the answer to the riddle lies with the Japanese, we have to know what it is they're worried about. As a student of Japanese culture, I can state confidently that in their daily life the Japanese are mainly plagued by the following three things:
1) Men who molest women on commuter trains.
2) Gangs of Tokyo drifting teenagers.
3) Animated pieces of feces.
Which leads me to conclude that the monster in Cloverfield is a 40 story turd that slides around in an unnatural manner while molesting women.
So probably not a date movie.