Fun experience overall. I liked Mizuki's route the best, which seems to be a pretty common reaction. If there's going to be a sequel (which the game doesn't really need, unlike 999 it wraps up with only a few dangling plot threads), I'd want it to focus on Mizuki the idol magnate and on the AI tech. We never really find out where Aiba came from, beyond "Pewter made her." I was half-expecting to learn that she was created from someone's connectome, but we never really met any characters who were a good candidate for that.
On reflection, is Mizuki's route likely a 'bad end' with the story's full context? Pretty much all of the main characters'
bodies lived, but... Iris had her eye yanked, which (if I am following the swapping shenanigans correctly) means that So Sejima is currently inhabiting her body, and Iris' mind died in Renju's body. Will be a bit of a nasty shock for all involved when that comes to light.
Twist-wise, I'd guessed at the body-swapping shenanigans, though I wasn't sure of the exact mechanism until the 6-minute-psync reveal occurred. I didn't follow what was going on with #89 and "Falco" until that actual reveal happened. They also got me on the Manaka/Iris body switcheroo; I really should have paid more attention when Hitomi dropped that clue about her classmate.
I was mostly fine with the game's non-horny goofy bits. Aiba's Somnium-entrance gags were usually pretty good, and I'd be lying if I said the final dance number didn't put a smile on my face. The action scenes with everyone diving for porn mags were just lame, though, as was Date's constant commentary. I hoped that last was just a symptom of his off-kilter brain chemistry in Saito's body, but he seems to have kept those traits in the epilogue. It's hard to see the horniness as anything other than an author self-insert, since it seems rather out of character for the Falco described by Iris and Hitomi during the time they knew him.
Aside: I've heard speculation that sci-fi author Robert Heinlein's sex obsession in some of his mid-period books was related to brain issues from a blocked carotid artery, and that
after his surgery he reverted to his earlier style. That feels like it would have been good material for one of Uchikoshi's science explainer sequences in the epilogue, if they'd wanted to throw in any explanation at all for Date's 7th-grade level sex obsession.