I think the leaves would be better if they were on different planes and maybe rotated a bit depending on where they are.
Something like that. Obviously not and accurate drawing, only took me ten seconds to do, but you get the idea right? Also get a few more leaves to fill out the gap behind those five, otherwise it'll just look weird from the back ;P
Otherwise, I think the only other thing that bugs me, besides what's already been suggested, is how thick the outlines around the eyes are. On the leaves it looks fine because the leaves are large enough to justify it, but the eyes are so small that a thick outline like that just overshadows them. The outline is also a bit blurry, that doesn't help much ;P Something more like what you've got for the mouth now would work best I think. Otherwise, good model, I really like that leaf texture for some reason. I don't know why, but every time I look at this model I have to stare at it for a few seconds. It's hypnotic I swear.