Your style has shown great improvement over a short amount of time. the lines are smooth, expressions are more unique and the attention to detail is remarkable. As for the story, this is a great example of the Doctor's ability to think a step or two ahead of his enemies. The use of the Sonic Screwdriver as a "magic wand" as some, including myself, would put it does weigh this down quite a bit; however, the overall understanding of the character and his capabilities shines through. You clearly have a great story to tell here and I can appreciate that.
First time critiquing, so just go with me on this one. I hope to see the new one soon, as I just got set up here in Texas.
Vision: It is easy to see that you have an idea what you're doing, and what you plan to be doing later. You make each new step of this story easily followed but not too obvious, so we have to keep thinking, wondering. It's great. I'd say you have more vision than Foresight!
Originality: It has been a long while since you started and lot of Doctor Whooves stuff has been done, but you've made it your own! You have taken the character, made him as Doctor Who as possible, and made it as pony as one can (other than the innocence, which is and isn't missed). You have taken characters we know and love, and made them your own, given them a life in this story not many have even thought of!
Technique: I love the way I've seen your paneling change, how great it looks now. The art has been great for a while now, and I have enjoyed every new piece that comes. The story looks fresh, like it could be printed and sold!
Impact: When I first stumbled upon this I thought, "Oh great, more Doctor Whooves, no one ever does it how I like." You didn't start the story how I feel it should, but you have shown me the way and made me think "Derpy is good, I'm okay with this." I have taken yours as the only true Doctor Whooves, and I get giddy when reading. You are a great writer, and an amazing artist as well. I'm jealous, and inspired.