OK, seen the episode now.

Spoiler
Show

WHAT. A. COP. OUT! So, it was the tesser-whatsit robot on the beach...which somehow managed to simulate the first signs of a Time Lord regenerating, and which nobody noticed hadn't burned in the boat. And all the Doctor's angst about all the harm he's done over the past few episodes evaporates like snow in a desert all of a sudden. The tonal shift was jarring and awkward and set the seal on the awfulness of the whole thing.

Moffat has done what I previously believed was not possible--he has produced a worse season ender than anything Russell T. Davies ever managed.