The Ultimate Foe! What a remarkably accurate title for a change, no inaccuracy here! I don't know if the resolution to the trial of a time lord makes a lot of sense, but what a brilliant way to end it! Now then, unless you have been living in a cave, in Mars, with your fingers in your ears, you will know that the Valeyard was in fact the Doctor himself, in his twelfth and last regeneration, and that he wanted the sixth Doctor (himself) dead so that he could steal his remaining regenerations for himself.
Absolute rubbish? Possibly, possibly, but an ending surely noone could have predicted. and is it all that unlikely? Here is a future incarnation of the Doctor, possibly thousands of years into the future - it is likely to assume that a person's priorities might change in all that time from good to evil, even the Doctor's. And he was facing death after his next regeneration, so was presumably desperate enough to try drastic measures to prolong his life - for a time lord who's lived so long, death when it comes must be even worse than for a human.
I also loved Mr Popplewick who was (cave in Mars, fingers in ears) also the Twelfth Doctor. I would like to see a load of new adventue novels featuring Mr Popplwick in a Tardis, maybe slowly tranforming from good to evil. No? Oh well.
But a good ending to a good series. On the whole. I personally thought that there was a bad Sixth Doctor that we were seeing on the matrix screen - a doppleganger who we were seeing doing all those bad things, and not the good sixth Doctor at all. Well, it seemed plausable at the time!