Solid first half of a two-parter. I'd give it a 7/10 because I think that's the most accurate, but in the system I'm giving it an 8 because of the inevitable review-bombing.
Not the best thing ever, awkward moments as always, third companion made useless again (in this case, Ryan). Whittaker's Doctor has become slightly less stiff with every passing episode, as they have given her more emotional moments as well as characterisation. Her happy-go-lucky persona has been clearly an overcompensatory charade and it's been steadily breaking down over this season, and she is snapping more at her companions and other characters, which hopefully paves the way for 13 finally coming into her character in the following series.
I liked the segments with the Irish Guard -- was the cliff scene a nod to Chris' work on Broadchurch? I certainly got that impression.
Doctor Who has never LOOKED this good -- we HAVE to hand it to the sfx team, and the prop designers, and cinematographers and other crew, even if the scripts and direction are still awkward in places.
Solid episode -- like Fugitive and Villa Diodati, shows great promise for the show going forward and moving past the stiff, bland and poor series 11. I was worried about this finale after the unmemorable and poorly-constructed Ranskoor, but I am hopeful going forward. Not a perfect story -- people must remember that even the episodes of Doctor Who they remember most fondly are definitely far from perfect; the show always has been (except for Heaven Sent which is absolutely without flaw ;) Some stiffness remains but it's been noticeably allieviated.
Sacha's cameo as the Master was very abrupt but he plays the role well and I can't wait to see more of him in the series.
My only complaint is that I didn't get to see my girl Ruth -- I hope she isn't just reintroduced and discarded in this final episode; I'd love to see more of her going forward (anyone else want her to be a future Doctor? Anyone...?) and I think her arc is much bigger than what two episodes could ever conclude meaningfully.