Not everybody is going to like this episode, and I can see why some wouldn't enjoy it. You definitely need a good appreciation for the River Song arc and this character to enjoy this, and it feels like a truly lovely way to sort of close out her story (at least with the Doctor).

Humour is tough. If you find this episode funny, odds are you are going to like it. If you don't, well, it is all going straight out of the window. I certainly found a lot of stuff funny myself, most notably Capaldi's fake reaction to the TARDIS was just excellent, while the "hello sweetie" line was also pretty silly but also full of sentimentality.

Moffat is a bit of a self-indulgent writer who seems to sort of clap himself on the back sometimes for how clever he is within his own scripts. It bothers me sometimes quite a bit but here it feels deserved. After everything he put into River, after all he did to maker her one of the most unique characters in Doctor Who, the dude kind of deserves to have episodes like this. Nardole, on the other hand, is at his absolute worst here. His jokes are the least funny in The Husbands of River Song and it is actually a bit misleading in that this character gets far better in Series 10 but did not leave a good impression here.

Whatever the limitations of The Husbands of River Song there is, and they very much are present, I can't help but enjoy this one and kind of view it as a must-see whenever I'm revisiting this era of Who. It's so lovely and a perfect ending for River, tying up with Silence of the Library in a way I never actually expected them to fully follow through on but really fits nicely with what we know happens to her. A huge step forward for the franchise after, in my opinion, a pretty catastrophic finale for Clara in comparison.