Rassilon!
I think that was the high point of it for me. My brain went "yes! finally! something other than an ood!"
Don't misunderstand. Yes, it was sad. I was horrified to watch the Doctor die. And it really was one of the best episodes Russel T. Davies has written.
I just wish he could have lain off the ood obsession that one time. Just that once.

I liked how it gave some more explanations with regard to the time war. The timelords having gone Dagenham, for example. It explains a lot. They always did seem rather dodgy. Even in the old days.
But Rassilon! Whooow. I did not see that coming. And I love how they just buried it.

I also wonder who the woman might be. I had her pegged for the white guardian or some such until she showed up at the end. That theory was obviously wrong. I am thinking she might be Romana, but then I don't see how that could happen.

And I loved the fact that the knocking was a misdirection.

I may have more comments when I get round to it, but those were the first main ones.

Edit: Oooh, I thought of another thing. Did the 10th Doctor try to kill the 11th? He did say that he thought the Time Lord lived too long, and then he sat the controls, and when 11 got round to it he remembered the Tardis was crashing. Which suggests it was set to crash.

Edit2: And I loved how he introduced Captain Jack to Alonso. If you can't have Ianto, I am sure he is the second best.