Not great, though moving Antiques Roadshow to BBC2 and running them against each other was a weird move. AR always gets a solid rating in the same way something like Countryfile does, it's a Sunday evening BBC staple.
Anyway, I watched the episode last night and it was... OKAY. It felt more like a mid-season filler episode than a one-off special, though I enjoyed the guest cast even if they weren't as fleshed out as they could be (a bit of a trend for this whole era really). There was some dodgy editing and effects work, though the shots of the TARDIS at the bottom of the ocean were gorgeous. The scenes between the Doctor and Yaz were the best part, there was a proper acknowledgement of their mutual feelings along with a decent reason for them not to get together; it makes sense for the Doctor to be more closed off the older they get, though I'm still hoping we get some sort of happy ending for them in the final special. Somebody online suggested a montage of them having a lifetime of adventures together until Yaz is an old woman and eventually dies with the Doctor (still young) by her side, and I keep thinking about it.