Is it amazing?
Yup.
Nuff said.
I thought it was good and oddly Moffaty for the first half...
And then the line of awesome win of "I can't die until he knocks at the door four times! I've got a pretty good idea who that is and I don't hear any knocking!!!" Bam- Bam- Bam- B"THAT'S ALL YOU GET!" (quoted from memory not looking it).
But... for that last 5-10 minutes? Oh my goodness...
Seeing him become the Master (the Master whose working for good?) Amazing... and the perfect tie in. I still am not looking forward to losing Tennant but... it really makes it necessary. Having him power trip like that and damn but Tennant's a good actor. I say this because you could SEE it dawning on his face. Literally. The slow utter awareness of "I'm a Time LORD. I'm a TIME LORD. I CAN DO WHATEVER I WANT AND I'M GOING TO DO IT BWHAHAHAHAHAHAHAHAH"
And having her shoot herself...
Not my favorite episode... the top three or four or so are still reserved... but definitely one of the most epic. I think in many ways more epic than the season finale, just for that last 10 minutes. .