Nagisa is surprisingly wise for an elementary school kid. I guess that makes sense, considering his backstory
I actually don't hate any of the kids (except Monoca, but even her to an extent is redeemable) because of things to be revealed
As for the anime:
-Everything felt rushed, but I tally that to the anime format where they don't have as much time as a game
-A lot of the characterizations felt off, Mikan and Mukuro, and all of the Future Foundation members. People thought that possible routes weren't taken, and their characters were reduced to simple archetypes.
-People felt like the "despair video" was too simple. The ending of DR2 had people expecting Junko to break down each of the 77th class one by one, instead of just converting the whole lot using a live feed with Ryota's "anime talent".
-Tengan as the mastermind felt really off, and his plan felt full of fulls. If he wanted Ryota to use the hope video by killing off the Future Foundation, why was Ryota in the killing game? People have noted that Tengan was surprised when Ryota came to the meeting, and that his wrist band could've been meant for Hagakure, but couldn't Tengan had moved Ryota out of the building when everyone was knocked out?
-There were a lot of good character development routes they could take, but they didn't