I'm still working my way through Season 4 (I know, it's my hoarding tendency again) and Donna has grown on me. I HATED the idea of her as a companion at first. But I agree with Katebo's take on her personality, and I have been impressed with her dramatic acting ability. Plus, as much as I love the 'shippy aspects of Rose and Martha, it's nice to have a sidekick who is all "no, seriously, we aren't a couple, not gonna happen".
And yeah, I'm so over the Daleks. But I've just grown to accept that they are going to eventually revisit any bad guy from the classics who had any fan love at all, probably repeatedly, and just hope they manage it okay. But the Eccleston Dalek episodes were far and away the best because they allowed the character to bounce off the enormity of what he had done himself, and what he had sacrificed, apparently ultimately in vain. The continuing return of the Daleks is reducing their scariness as the ultimate bad guys but it's fan service that they can't seem to avoid. On the other hand, I always found the Cybermen ridiculous in the old show (and the Sontarans as well) and both have been not only successful but even scary bad guys on the new series, and so far not as overused as the Daleks. But I am getting to the point of "Good lord, what DIDN'T survive the Time War?"
CSSchneider - as much as you probably heard my howl of angst from where ever you were when they announced Tennant's departure, I've made peace with it. I loved loved loved his Doctor but it really was a good time for a change. Similarly I will love Russell T. Davies forever for bringing the show back so successfully but he had worked through all of his ideas for the show and was beginning to repeat. When Tennant doesn't have enough meat in an episode, the manic stuff or the lonely god stuff can really begin to grate.
Having two Doctors who literally had the weight of the universe on their shoulders and were dealing with the enormous consequences of multiple genocide was a great way to wipe out memories of the lameness of the last few years of classic Who and the movie disaster, and led to some really great storytelling. But Matt Smith seems, so far, to be a Doctor who is primarily about the joy of life and new adventure with a side of darkness, rather than the opposite. I didn't realize how ready for that I was until he arrived.
Tom Baker will always be "my Doctor" but Tennant and Eccleston are right behind him in my personal pantheon. And every time I go back and revisit Eccleston's season, he *almost* edges out Tennant, and might have had he had longer with the character.