Otherwise, we're forced to wonder why we would have a mile-long Federation battlecruiser with minimal crew (as stated in the movie). Sounds like Star Wars, to me.
It's explained in the film for why it exists, and said reason is fairly easy to see considering the incursion of Narada and the death of Vulcan. It can run on one crew-member if need be.
Enterprise seemed quite large in the movie; several hundred meters didn't seem too out of place going by eyeball.
Incidentally, the small Klingon vessels are referred to as a D4. Also, the transport that the heroes utilize (the one in the trailer) was said to be Mudd's -- comic book and/or TOS reference there.