I didn't think it was that shaky, at least it was no more shaky than his usual stuff. The only point that really bothers me for some reason is that (SPOILER) John Hurt/Tennant/everyone before 11 is going to forget the events that happened in this episode. That makes sense because otherwise it would make no sense for none of the doctors to ever bring up such a big event in their lives. My thinking is that everything with those events, including the memories of them, have been time locked. This stuff had happened all along, The Doctor just sort of didn't remember that he didn't cause the death of all of his people. If that's the case, though, 11 shouldn't be able to remember either.

I'm guessing the actual explanation is that timey-wimey stuff happened and there is no explanation. Everyone except 11 forgot what happened because time and space is weird.