Easy now!

Ok upon first glance this piece looks really good, then as I perused around the piece a bit more I found little things that made this less appealing. Now just remember that this critique is coming more from a viewer than a teacher of art.

So first thing I noticed was that the proportions of the female's face are off. The nose and lips could be spaced slightly more and they both could be scaled down slightly.
Now I understand that the piece is about the people which is why you can get a away with the back ground being not as detailed. You use that way of painting so that the focus of it remains on the people. I personally have never been a fan of this. Now one thing that struck me is that the people are so perfectly rendered with shadows and highlights yet the background seems to be lacking a little darkness and all the highlights. Once again this could be style but for me it's not appealing.
Other than that, it's really good. I like the way the nipples are hardened and hanging over the forearm a bit and how you've painted the tattoos on her arms. Only thing about the leaves is they could use some more variance of color, though other than that, It's solid.