I don't normally do critiques, but I'll give it a shot since I liked this piece very much
Firstly, I'm no expert when it comes to anatomy, but taking a close look at all the small details and proportions, I can easily say that you have a good idea of how a woman's body looks like, and this is at least one of the best humanizations I've seen so far. Bonus points for the fact that there's absolutely nothing bugging me in this piece.
You also nailed the expressions. Varying degrees of want... perfect.
Secondly, I just love your style in general. I don't see many of those pictures (I don't know if there's a name for that) that don't have an outline, and usually people just can't do it right, but yours looks very clean and original. Good work.
And lastly, while the concept itself is not that original, there's something about this picture that I've never seen anything like, but I can't put my finger on what. And although it's not the most... controversial MLP picture I've seen, it certainly is your most controversial MLP picture. If this was a result of your laziness, then please be lazy more often.
In conclusion, this is outstanding and very sexy. I can't think of anything bad to say about it. Excellent work.