Doctor Who: The Time Of The Doctor
Without going into detail [as some might not have watched it yet] It does answer some questions while leaving other long standing questions open to further discussion.
What I can say is that I enjoyed the episode more than I expected I would. If you haven't watched it yet I am sure that you will like it. Thumbs up from me.
Behind The Lens - The Time of the Doctor - Doctor Who: Christmas Special 2013
Note: This video includes some episode spoiler content.