Gloriously ridiculous and funny in a way that reminded me a lot of the Hartnell stories The Romans and The Myth Makers. I laughed with it a lot, and was pleased to see Clara taking the initiative and pumping the Sheriff for information. I like that the current series - while it certainly has a story arc - is looking more like an anthology of different stories with different tones, which is how I felt much of the older Who was. Still very much loving the Capaldi Doctor.
Further thoughts (none of the criticisms stopped me enjoying the hell out of the story):
Merry Men: apart from Robin Hood, there wasn't much to them, which was a shame, although giving most of the airtime to the annoying minstrel was a lovely Pythonesque idea. They laughed a lot but overall fell a bit flat and it made the Doctor's theory that they were all robots or exhibits in a Miniscope a lot more believable than that they were real people. Which I suppose at least hid the twist.
Ben Miller: someone sign him up to play The Master; in a role that would have been easy to overplay, he was pitch perfect in every scene he was in, of which there were fewer that I'd have liked. I'm also currently working on the assumption that Missy has added him unseen to her heavenly collection.
Golden arrow: everything about that was utterly ludicrous. The robots are short of gold, but don't care about other gems and precious metals - so they cast an arrow out of gold and let the bandits run away with it. Later on, that same arrow fired into the side of the spacecraft somehow provides enough shielding for it to leave the atmosphere, but not enough to stop it blowing up at a safe distance. And gold's heavy - an arrow made of it would fly terribly. It's like they saved up all their stupid for that one plot element. That said, I did like the design of the spacecraft; agreeably different.
Turkeycock: because we totally had turkeys in twelfth century Britain.