It's enjoyable throughout, but overall feels like a more overstuffed and less fun (and significantly less comprehensible) The Five Doctors. The more I think over it, the more it falls apart.

I unfortunately got little to nothing out of the returning companions, and felt that their moments of showing off ("I was an air hostess in the early 80's, and, trust me, compared to that, a building full of Cybermen is nothing") were more eye-roll inducing than anything else. Tegan could've (and I argue should've) been safely cut to give more time to the myriad of other plot-threads.

Sacha Dhawan's Simm-Lite performance has fully crossed over into being irritating, I unfortunately didn't much enjoy him in this episode. There's something there - his "Don't let me go back to being me" line is outright great and shows a hint of what could've been a much more interesting characterization - but we don't get more than a few glances at it, it's instead left to be assembled in retrospect by fans.

Jo Martin, as always, steals the show and makes you wish you were watching the version of Doctor Who with her in the lead. That she got less screen-time than Graham (not even being physically present!) frustrates me.

The decision to have the Master's plan lead to him in 13's costume, rather than giving the outgoing lead the opportunity to show a side of her performance we never got to see is so irritating, I wish that we'd have seen more of 13 being angry, intense, something other than her usual awkwardness.

Finally, the Doctor's treatment of Yaz's feelings is so rough, and I'd argue queerbaiting. Their last conversation before getting ice cream was the perfect opportunity for a kiss, or a reciprocation, or something; but instead we're left with Yaz being ditched in 2022.
None of the remaining threads are acknowledged (her being stuck in the 1900s for years!) and.. that's it. It's bizarre - why glance at a queer relationship if you're not going to do anything with it? It's like a worse mirror of the exchange between the Doctor and Graham in Can You Hear Me?. Even having an off-screen relationship between Legend of the Sea Devils and this story would've been better. A capstone to an era of missed opportunities.