This is a very nice piece! I especially love how you added the bits of the episodes Chris Eccleston was the Doctor in. The lines are very well defined, and even though there is a lot of things in this image, it doesn't seem too cluttered. I really like the percpective you've given the Doctor with his hand-dandy screwdriver.
I really like how dark Chris's face is made, because, to me, Chris was a vey dark and mad Doctor (compared to David Tennant, who was a very happy, hyper, VEY MUCH ADHD character). You can see the lines of worry and little bit of age on his face, as if he's been through too much, but he still tries to put on a smile.
Also, I don't know if you realized it, but the way Rose's right hand (on our left facing us) looks like it's becoming the Doctor's hand, and I find that absolutely amusing, and kind of makes me think of her really trying to stay with him because she loves him.