From what I can see, the model looks good. The skin size is a trivial issue, since resizing is the work of a moment. If the model is going to be sold, a 256x256 and 512x512 skin can be included, for that matter.I have the idea that it's best to use powers of two for skin sizes, though there seems to be some debate about that.
Suggest you follow Blattsalat's advice and post a larger picture of the Stuka, if you want more reaction.
Regards,