A lot of my feelings got summed up here: basically, the episode had a lot of momentum and incoherence. Beyond that,

• Having just watched "Pyramids of Mars," I'm puzzled Davis revived this villain, and that the impatient Sutekh acquired the patience to wait centuries (millennia?) to complete his plan.
• I love the Memory TARDIS!
• I thought 15 was supposed to be the "healed" doctor.
• Davies is playing with the idea of concepts, perception, memory and faith influencing reality; but the handwavy, cursory explanations for how it all works makes it impossible to anticipate events or solutions to the challenges thr Doctor faces, which limits how the viewer can interact with the story and how engaged I feel. (E.g. when the Doctor says "there's nothing I can do" we just have to take him at his word, until it turns out all he had to do was leash Sutekh and drag him into the time vortex, and likely could have from the very start, given how Sutekh was restraining himself even before they discovered Ruby's mother. So the show becomes less of a thought exercise, more of waiting for the Doctor and plot to strikefamiliar chords.)
• This isn't Davies' best work, but I'm hoping he's getting back into his groove. Either way, I'm hyped for Moffat's upcoming special!