I am going to have to side with remembrapril and his review. Yes, it was interesting and touching in many ways, but it violated a Cardinal Rule of Doctor Who continuity. That is: The Doctor cannot intentionally go back in time to make his present situation more favorable. That has been stated repeatedly. For instance, after the death of Adric at the end of Earthshock, The Doctor cannot go back in time to save him. If this is something that becomes a trend, it can easily become a deus ex machina plot device that can be used as a "get out of jail free card" in any circumstance. In fact, if he fails to do this in future episodes, then it will beg the question, "why doesn't he just go back in time and...?" The precedent has been set. As a stand-alone time story in the general "time travel" genre, it works. As a Doctor Who episode, it fails.
Review of A Christmas Carol
