It was a very cool concept. I do have to admire the vision of it, but it just felt disjointed, like something else should have been included to make it whole.
Such as, why were we never given a nod to River going to the Library in a past episode? And no, I don't feel like those mini episodes really should count. Let's find a way to plan and pace the show proper and make it actually happen. Those things are like, when a game manufacturer makes a game series, then releases hand held sequels that aren't just fun side filler, but important to the actual plot *coughKingdomHeartscough*, forcing you to pay hundreds of dollars on things you don't want and will probably never use again once you are done just to get the whole story. That's when I stop caring about the franchise and no longer play the games. :/
If Moffat's reason for not including The Doctor sending River off to The Library was because there was a brief mention of it in "Night and the Doctor," then that just seems kind of sloppy. The mini-sodes were fun, but shouldn't be used for huge plot points. She was all good and fine in the first half of season seven, then is just dead for a long time at the end? At the very least a brief five second nod to the event would have been appropriate.
It's kind of the same with Vastra, Jenny, and Strax. As characters, I do like them, but it always bothered me that they were never introduced. They were just magically there, The Doctor's closest friends who have seen him through so much pain that he trusts so completely.
This individual episode itself was good. I enjoyed all of the nods to past Doctors, and Clara telling The Doctor which TARDIS to steal was kind of funny. Clara was pretty much Bad Wolf 2.0 as I figured she would be, which I did enjoy. But looking back to view the season as a whole as one story, there was so much missing.
Not to mention I still don't find Doctor/River to be believable. This episode didn't really change that. I had been hoping something would come along to cement their relationship so that I could actually get into it, but nothing ever did. I just found myself asking why, mostly. Why did The Doctor care about her so much? When did he really start? Hell, I have the same questions about River and her feelings for The Doctor. I don't see a believable beginning for her. I don't quite understand where along the line she fell so deeply in love with him.
At this point I would believe a love story between The Doctor and Clara more than him and River. Hell, I think I would have found Doctor/Amy more believable as well.
Especially because River knowing The Doctor's name is a very monumental thing. It would have been nice to see him tell her. It would have been nice to actually see him grow to trust and care for her enough to do so. We were never shown this, we were told. Told that this is the way it is, just because the writers say so instead of the plot actually leading us there.
So many great concepts, but same with how I felt in the second half of season six, not a very good presentation. I feel like Moffat is trying to make the show flashy and timey wimey to the point of sacrificing coherent plot. All of the "good points" of the these past two seasons seem more cosmetic than anything.
In essence, Moffat = George Lucas of British SciFi? Because his episodes were so good when he wasn't the one in charge. I sure hope the 50th is good, but honestly I don't know if I'm as excited about it as I was pre-season finale.