I... don't... really know what to say about this one.
I'll be honest up front and say I actually liked it more than I anticipated -- I might almost say "enjoyed", but that might be too strong a word. I didn't hate it, which these days from a Moffat script feels an awful lot like loving? How the turntables, etc. My expectations were as low as they could possibly be, so I guess it's not hard to believe the show sort of... failed to be as utterly terrible as it possibly could be.
In other words, it wasn't "The Wedding of River Song".
There were lots of bits that made me roll my eyes, but none that struck me as outright morally heinous, so that's always nice. Clara's "impossibility" was what I'd predicted since BOSJ, so I felt validated, and even better it was something she chose to do (in as much as one can choose something they've already chosen) rather than something that happened to her by force (like River) or by coincidence (like Amy and the cracks). So... baby steps, right? And it was fun to see the TERRIBLE cgi of Clara blitzing through Classic Who.
Like all Moffat finales though, it falls apart if I think too closely about it. If Simeon (somehow, and irrationally) made "all of the Doctor's victories a failure" and Clara fixed that, this implies that Clara did literally everything that ever happened in Doctor Who. All of it. And that's silly. And we KNOW he "never heard her" or noticed until AOTD and The Snowmen. So if I just ignore the logical implications and assume that the only Claras who ever meaningfully interacted with the Doctor were Oswin and Victorian Clara, uhhh that's fine, I guess. (Also, lots of opportunity for jokes: was the woman in the shop who gave Clara her number a Clara herself? Susan's friend and classmate from 1963, Clara Sandiego?)
Eleven/River remains hilarious to me -- so she's been dead since TATM? What the fuck? Since when? If I shipped it or cared I'd be outraged that we never saw the Singing Towers of Whatsitcalled, and that we never had any indication until now that Eleven considered her dead and gone and mourned her. But Eleven/River shippers and I rarely agree, so I imagine they're quite happy they got a poignant goodbye and a kiss. Is this the last we see of River? Praying to the old gods and the new, personally, but I don't understand logically how we can know that, because surely he could run into another River at any time. (They're not running backwards, despite what Moffat wants me to believe.)
AND of course... the "big reveal" in the end. I can think of several ways John Hurt as this lost, alternate, whatever version of the Doctor who did something terrible and secret might be very interesting. Unfortunately I can almost assuredly count on Steven Moffat to choose the worst of all possible scenarios, so stay tuned for November.
For those who don't frequent Tumblr and may not have seen it immortalized in gif form yet, they also released this:
Much as I may fear what Moffat has in store, I can't say no to an interview where David Tennant talks about Doctor Who while dressed as the Tenth Doctor on a surprisingly flat hair day.