I used gregmartin's tutorial on how to make a realistic starfield. It took me 2 days on Photoshop 5.5 . I had problems trying to create the stardusts that I really wanted. Anyway it was fun doing thos ...
Personally i really do feel that 'flying craft' is out of place... maybe it's because of the cloudy and windy scene effects are not enough. I think is the sense of dimension....
Yes indeed a very beautiful work, the clouds are beautiful. There are alot of rooms to improve your art here, like what animagic mentioned, you may need to do something about 'sense of scale' .