Ugh.
It wasn't really bad, and it had a lot of nice moments (especially the museum presentation on the mysterious Centurion, "Fezzes are cool" and "...something borrowed, something blue"), but – to quote the Prisoner Zero version of Amy from The Eleventh Hour – "what a disappointment you've been." The tone was all over the place, half the solutions to the problems didn't even make any sense, and the cliffhanger from last week was resolved in 30 seconds in the least dramatic way possible. And to top it off, they managed to take the Doctor crossing his own time stream to deliver a message to Amy in the past while he's being wiped from existence and underplay it. Some of that is the result of heightened expectations, I admit, but frankly, the Doctor's time reversal back to "Flesh and Stone" was far less interesting than what I'd imagined the answer could be.
I guess what I'm trying to say is, the finale suffered from the worst flaws of the RTD finales but without any of the grand, emotional operatic scope that made those often irrational stories work. Boo.