Enjoyed both parts of this story arc - the dialogue is witty, and Matt Smith was a lot more natural and engaging - his tweed clothing seems a reference to his "mad professor" style of playing Doctor Who, which is interesting.
River Song, as ever, an enigma, and her put downs (leaving the brake on, etc,) were excellent.
Amy still looks a bit - unused. It seems the season story now revolves around her, but she's still not really doing much - or so it feels. Wondered if she were a young River Song as well, but perhaps too obvious - maybe the reason River doesn't recognise her is similar as to how Amy has forgotten the previous Doctor Who events (as with the soldiers who wandered towards the light as well).
Killing a good man? Seemed implicitly about the Doctor, which is very very interesting. However, considering the James Bond intro and the fact that the Doctor regenerates, there's obviously going to be a lot more behind this than is immediately apparent, and not as literal as we're given to think.
Altogether, though, the series has continued at a pace, the budgets are better, the actors look natural faster - the only danger I think is that the pace may be a little too fast to keep comfortable with. But we'll see.