That's a wonderful picture, especially if you drew it from your head. So, here's what I think of it.
1.I think it would look a little better if you defined the lines between the wing membrane and the arm bones more clearly. Since the membranes stretches across the bones, it would look better if the bone lines (around it's fingers? Or are they called claws?) are crisp at least in the middle.
2. I love the eye. It's expression is powerful.
That's about it. I hope this helps; I've never drawn creatures like this, so I'm not sure.
Keep drawing! ~Lava
~ Pretending in words was too tentative, too vulnerable, too embarrassing to let anyone know. - Ian McEwan in Atonement
