Towards the end of the story he explained to Clara that The Doctor had used up all 12 of his regenerations. He's routinely known as the 11th Doctor, which would mean 10 regenerations. BUT ... there was John Hurt's War Doctor, who he didn't really want to refer to as The Doctor, but that counts as a regeneration. And then the 10th Doctor had a regeneration but kept the same body. That adds up to 12 regenerations, meaning the Doctor was out of regenerations and while he was shown as having aged a whole lot (perhaps 4-500 years in one place, plus the 200+ years prior) if he died it would have been his last lifetime and he would actually be dead.
And, yes, the previous time at Trenzalore we saw his grave. And we saw a planet that had burned in a futile attempt by the Doctor to do something or other. Meaning that, for the Doctor, Trenzalore was a "fixed point in time" because he'd seen his own grave/tomb. And now he's gone and rewritten that piece with an interesting gift from the Time Lords.
Which makes two major rewrites of history in two episodes. First, the rewriting of the Time War thing which occurred in November's 50th anniversary special, and now the rewriting of Trenzalore. Both are "fixed points in time" in a major way, and now are completely different. One wonders what the impact of this should be.
That is, we've been told this idea that fixed points in time are just that, unchangeable. But the Doctor, being one of the biggest time meddlers of all, welll...
With the 50th Anniversary special, and with The Name of the Doctor, we see that the whole story arc of the Doctors life has been about rewriting the Time War so that Gallifrey didn't have to be destroyed.
Now that it hasn't been destroyed, it has been pushed over to a pocket universe for safety, and the Time Lords are trying to get out. How they're trying to get out is through a Crack, the Crack that began the 11th Doctor's lifetime, the one in Amy Ponds' bedroom, but a version of that crack on Trenzalore.
Turns out the whole Crack thing was created by Madame Kovarian's break-off group, who splintered from the Church of the Papal Mainframe during the Siege of Trenzalore (shown in this episode) to go back in time, try several ways to kill the Doctor, including blow up his TARDIS causing all the cracks in the first place. So, when Kovarian kept cursing about the War that she wanted to stop, she was referring to the Time War.
Are we to believe that the Time Lords can pilot the crack they're using? That they can close that crack at will, and move it around? Hurm.
What do I think? Other than the unnecessary nudity (was that really necessary??? NOPE) and unnecessary sexual allusions between The Doctor and this new person, Tasha Lem, (was that really necessary??? NOPE), it was good. I liked it. Not exactly jumping up and down excited, but it was cool.
It seems from some pictures we've seen on Facebook that the next period of Doctor Who (not to start until August) will be a Quest to find Gallifrey. Oh, and getting used to this new guy.
Here's a thought in closing: