Pike got his "that's rough buddy" moment.
I am very glad we got to revisit this storyline. There was a lot left to explain in that dimensional prison, and using it as a finale to neatly wrap a lot of different plot threads was great. I was really interested in that guardian figure from the earlier episode, knowing now that it ended up being Batel in a kind of asymptotic time loop is pretty crazy, but it is a very poetic ending. She can't really live a life with Pike, and this is an ending that gives her meaning.
When Batel's hands started glowing for a moment I genuinely thought she was going to regenerate à la time lord. And in the end I guess she kind of did! I half expected her to start babbling about some cosmic koala when she had stars in her eyes, I'm glad she didn't. The ending took a serious tone, and that worked very well.
This episode uses what is effectively a dream sequence and those you have to be careful with. It works well here because the concept of time, cause, and effect have already been established as in play here so even if it never turned out as the actual in-universe outcome, it still feels like it has meaning. I note that the show giving us Pike's alternate future had he not (will he have had not? tenses are hard with time travel) got in the accident for me cements the fact that he really is going to end up as his future vision told him. There's no avoiding it now.
I am not sure I really followed a lot of the treknobabble in this one. I don't get how the entity managed to reconstruct itself, nor why there was a whole debate about phasers being complementary instead of additive. But as a plot device to get things moving it was serviceable. Also, just a note, if you're firing a stream of ANTI protons into the atmosphere, one would expect the antimatter to annihilate on impact with the upper atmosphere. I did find it hilarious that there's two massive red lasers with the same power as a star beaming in through the balcony and none of the natives there were bothered by it enough to get out of their seats!
The planet design was really cool, the big floating churchey architecture was giving me Halo vibes. It's interesting that the planet has no warp travel but still makes contact with alien races. I wonder if then the Feds would bother to help them out in the aftermath, or if they just left them to it. They kind of should take responsibility, given it was them that unleashed the evil in the first place. Even if it's just to loan them that eye regeneration thing for a few hours.
Overall, this was a nice finale, and given it didn't end on a pointless cliffhanger, and wrapped up most of the threads well, one of the better ones as TV dramas go.