This may be Moffat's weakest story, which admittedly is not saying a lot. It felt more like a collection of (sometimes really good) moments than a proper narrative, especially given the many plot contrivances and anomalies. I got the impression that Moffat thought it was more poignant (and perhaps cleverer) than I did. But then, maybe advance knowledge of certain things was a bad thing.
Liked the banter between the three at the start, and the River/Doctor interaction was nice. I guess this episode won't prove to be Kingston's swansong, as River probably turns up at the Fields Of Trenzalore and learns the Doctor's name. (I'm also a little surprised that Moffat didn't take the obvious narrative decision of letting the Williamses find out about River's fate and the Doctor's dissimulation in keeping it secret. That seems like drama gold right there.)
The transfer of regeneration energy feels like it's a setup for something. Could it be that River now has enough to regenerate, or that the Doctor doesn't? (The Ten-to-Ten regeneration should count as one or part of one, leaving Eleven with not quite two regenerations initially.)
All in all, I think Chibnall and not Moffat is this season's best writer so far, and it's starting to look like he's the heir apparent to the job of showrunner.