It's a nice piece but if you really are looking to fix it then take a look at that left eye. See it? the Iris appears to be filling the entire eye. Needs a bit of the Sclera showing (the eyes surface) and a dab of light. But you have achieved a really nice pic and a good likeness.
Oh my... my bad xD I was so concerned on drawing the Doctor, that I didn't put all my interests in anything else, such as... his sonic screwdriver. I'm still wondering how could it happened to be so short...xD
Very Good! Love it.... His screwdriver looks a little stubby though, but excellent! Want to know something really nerdy.... I can actually tell you the exact scene in which episode you're reference picture was from. Its the sene from "School Reunion" where he's in the school cafeteria , and he notices the chips taste funny. Imagine a fork where his sonic is,.. now put chips on it. That's what he's staring at. Or I could be wrong and making a complete fool of myself. Either way, I love the colouring, and his expression.