Personaly, I don't mind it being 900 metres long. If anything, it makes more sense to be that large. Any nation spanning hundreds, if not thousands, of planets with FTL travel and M/AM power sources, composed of numerous races that have been in space for centuries should be easily capable of building kilometre long ships. Old Trek was, as Kendall pointed out, very minimalistic in stuff like that. I don't mind nTrek deciding "fuck it" and building a big kick-ass ship, particularly since it's a completely alternate timeline.
Oh, and on another note I now have canon proof that my theory that time travel in Trek merely sends you to an alternate but similar reality is correct. So take that, naysayers!
![Razz :P](./images/smilies/icon_razz.gif)