Nicely written movie up until the end. This didn't need to have the sci-fi twist. Just come up with some other creative ending and give the movie a different title without any ties to Cloverfield.
It doesn't have any ties to Cloverfield though does it? I didn't get the impression that the Aliens in this and the monster in the other film are related. I started out assuming that the attack was a reference to the monster and that the 'flash' was a nuclear response to it but at the end when I saw an Alien spacecraft flying around I thought ''oh this is a different thing then''.
Maybe the name Cloverfield merely denotes that there'll be a fantastical element to the film, but it's actually an entirely separate story.....or I'm wrong....
edit - by the way I haven't read back through the thread, maybe this has already been discussed.