Amen to that! Besides minor plotholes a wonderful example for good television and for why Matt Smith is so goddamn underrated. Being the youngest actor in this role so far, his performance of this 1000+ yrs old alien really seems 1000+ yrs old - big talent.
Wow, that's a great essay. I pretty much assumed the Moment got them through the Time Lock (though it seemed a bit hand-wavy to me) but I totally didn't get all the Doctors coming in at the end. That'll teach me to finally start paying attention to the audio series! Anyway, it seemed clear to me that the Doctor didn't change the past so much as he changed the way he perceived the past. Sort of like the time-turner scene in Harry Potter. Everything had already happened that way, but he didn't realise it had happened until he made it happen again from the future, if that makes sense. I thought that was actually a really bold move, directly dealing with his genocidal past in a way that felt like a new start/redemption and still keeping the guilt of the older Doctors intact. It fits with the idealistic tone of the new series, that of always looking for the right thing to do (no matter how hard) and focusing on a better future. He finally stopped running away.
And yes, Matt Smith really is a wonderful actor. His Doctor is young and goofy, but in a way that feels as if it's a mask and a coping mechanism that keeps him sane. He does old-in-a-young-body well.