So, I found this idea that Yashiro, after his past encounter with Satoru, stopped killing and is not a serial killer in this timeline, even if he of course attempted to kill Satoru. It simply makes for an interesting idea as to where these two characters can go form now and what kind of relation they have. Like, Satoru could actually become someone Yashiro can confide in and fight the remaining issues he has, if Satoru were to forgive him (which he leaned towards, especially since his mission was a success and his friends were alive).
All that doesn't actually work in the context of the show because Yashiro was portrayed too one-dimensionally evil and we aren't really shown Yashiro fighting his conflict before Satoru went comatose. Of course we're now shown a short flashback to tell us this sort did happen in the meantime but it's just kinda weak. Especially when the episode beforehand doesn't make Yashiro out as some guy fighting his urges but a complete psychopath in that guinea pig monologue. Properly establish/foreshadow this change of behavior or it ends up like this feeling undeserved and out of place.
Well...that's actually all I considered partially good, really. The rest...
Satoru's speaking manner on the rooftop was ridiculous. I get that he has a master plan but can you tone it down some? Too high school level philosophy dialogue and tryhard psychology analysis.
The entire jumping sheet plan was far fetched to begin with (they anticipated that he'd be taken to the rooftop and forced to jump/pushed? Really now? And Yashiro doesn't once look down before letting Yashiro fall, either? Good thing Yashiro didn't just decide to cut Satoru's throat or something, especially when he apparently really struggled living without Satoru and may have been indifferent about what happens afterwards...
And my biggest complaint would be the very childish, fairytale direction the story took in regards to Satoru's friends. "Everyone remained nearby, close-friends with each other and Satoru, even going as far as shaping their life goals after his deeds! Misato, of course, started a fundraiser for him at the age of 10, despite not being that close to him at the time (even if she had a crush still)."
These kids were ~10 years old. 15 years passed. And yet everyone is still superbest friends? Next they'll force some random encounter with Airi as a way to end the show...oh no. These bastards actually did that.