That was very good indeed. In particular, the way that I assumed Rory was safe because we'd seen his future self was a very clever twist. And for all of us who wondered what the point of them seeing themselves waving - it was the obvious "They'll be okay in the future..." and then he wasn't!
Liked the negotiations, the failed rescue attempt, and the genuine attempts at peace. I also enjoyed another pace-change part way through the episode, when the chasing was paused for a look at the crack... and the piece of debris?! Loads of questions still to be answered... excellent!
One question: the Silurian soldier shoots Rory, who starts dying, and then starts being absorbed by the light. Why didn't the Doctor and Amy drag the soldier over to the crack and have *her* erased from history - if she never existed, then Rory doesn't get shot?
Otherwise, that was excellent - the best of new Who and with a very good classic feel. For me, one of the best of this season.