Disappointing overall. Not a great plot, and some dubious performances. Also the characterisation of the Fourth Doctor was all over the place, which Tom Baker did his best with, but sounded jarring. The recasts also threw me. There's a sequence where you hear past Doctors, but with some of the recast ones (presumably - 1 and 2?) I was totally confused. 3 was ok. Also Sadie Miller didn't sound like Sarah for much of the time. And Jemma Redgrave's performance seemed really flat. On plus Osgood was great, and the Monk. And it had what appeared initially to be an intriguing villain in an interesting location. But overall not good. Mainly down to the script.