As others have pointed out, the main problem with The Time of the Doctor is that it is too short. Or perhaps Moffat had too much to put in it. Either way, it leads to an episode with a few frayed ends where it has been stretched too thin. The whole family Christmas dinner, for starters, is basically pointless. What should have been no more than an establishing shot, a starting point for the story, is allotted too much screen time, the loss of which is only compounded in other places. For example, Mother Superious (Tasha) being Dalekified and then un-Dalekified in the space of a minute. That's no way to put us on the edge of our seats, Moffat, you have to build up the tension, then release it, not pop the balloon while you're still blowing it up.
Anyway, that can all be forgiven, which I can't say of my main objection: the Time Lords suddenly going all weak in the knees, giving the Doctor a new regeneration cycle and (apparently) just giving up the entire plan of trying to bring back Gallifrey. If that wasn't important, then why go to all the trouble? And hasn't it been established (in The End of Time) that the Time Lords are basically evil now and would rather destroy the universe than remain stuck in the Time Lock? So now we are to believe that all it took was a pretty girl saying "please" and that's that? Suddenly they all love the Doctor, and are okay with not doing the whole "getting back into the universe"-thing if it means helping him out with his bad back? Sorry, but no. I don't buy it.
That is, I don't buy the motivation. I accept that it happened. I accept that the Doctor was granted a new regeneration cycle and used it to defeat the Daleks and that it set up an excellent regeneration scene. I also feel that given the number of loose ends that needed to be tied up, we can take this in our stride and just be happy that it isn't Damon Lindelof who's running the show. At least we were given some fairly decent answers and everything mostly came together. I'm sure that had this story been given half an hour more to reach it full potential, it would have done so, and so I'm just going to imagine that it did. The canon stands, and I'm happy to fill in the gaps myself. But please, BBC & Steven Moffat, next time, take your time.
Anyway, that can all be forgiven, which I can't say of my main objection: the Time Lords suddenly going all weak in the knees, giving the Doctor a new regeneration cycle and (apparently) just giving up the entire plan of trying to bring back Gallifrey. If that wasn't important, then why go to all the trouble? And hasn't it been established (in The End of Time) that the Time Lords are basically evil now and would rather destroy the universe than remain stuck in the Time Lock? So now we are to believe that all it took was a pretty girl saying "please" and that's that? Suddenly they all love the Doctor, and are okay with not doing the whole "getting back into the universe"-thing if it means helping him out with his bad back? Sorry, but no. I don't buy it.
That is, I don't buy the motivation. I accept that it happened. I accept that the Doctor was granted a new regeneration cycle and used it to defeat the Daleks and that it set up an excellent regeneration scene. I also feel that given the number of loose ends that needed to be tied up, we can take this in our stride and just be happy that it isn't Damon Lindelof who's running the show. At least we were given some fairly decent answers and everything mostly came together. I'm sure that had this story been given half an hour more to reach it full potential, it would have done so, and so I'm just going to imagine that it did. The canon stands, and I'm happy to fill in the gaps myself. But please, BBC & Steven Moffat, next time, take your time.