Just to state a way I think you could fix your hands a bit is to define the wrists angles a bit more with better lines, making them more defined.
http://calibermengsk.com/gaia/redline/thaliat.gifO-o hope the image explains a little of what I mean for that XD Not really the best explanation.
Now, as far as everything else, it seems the girls stomach area is curved outward, and for the kind of person you seem to be drawing it'd be curved more inward then outward (even if she was sticking her stomach outward due to a reaction of the guy, there would still be some curves inward.) Also, it seems to be really pointy at her waist. As well, the guy seems to have heckuva butt. Very curvey, as most male buttocks would be more flat then that.
Besides that, it's a great composition. Maybe you should start trying some folds in the cloth on your next pic. It seems overall proportions are right... at least in my opinion.
As usual, this is just what I see, and you don't have to take any of it to heart.
razz Just some suggestions as to ways I would improve it. Hope this helps some
razz