This was a pretty terrible episode. In places, the plot was thin enough to see through, like an oily piece of greasepaper.
They mentioned that every sentient species in the universe had gathered above Trenzalore, ready to attack should the Time Lords make their way through or the other races move in. And then, they were handwaved away with a single sentence. Every sentient species in the universe. Gravitas was somewhat lacking there.
This is also the second time he's avoided the Trenzalore prophecy, which makes me wonder why The Silence take it so seriously, considering how easily it can be jogged around (repeatedly).
And, of course, they committed the very favourite cardinal sin of New Who: inventing new mechanics right at the end, to solve whatever predicament the Doctor is in.
Rrargh! Not happy at all.