Not too bad at all.
Seeing as how it's a shuttle, it doesn't need too much detailing in the model itself, the texture can make up for that.
I'm picking up the Art of the Film book tomorrow, so if you need any pics of the sketches for reference, I'll throw them your way.
The one direct nitpick I have with the shuttle so far, the front lights are two "headlights" not a solid bar. And the front window isn't that wide.
Other than that, looking great so far.
Something
somewhat useful, the Burger King toy:
http://img.trekmovie.com/images/merchandise/bking/Shuttle.jpgSure, it may not be as detailed as the movie, but it shows a "cheap" simplified version, which would be useful for making a model.