My opinion of it has soured over time, so take it with a grain of salt if you haven't seen it yourself yet. It was really fun lurking on the sub as spoilers flew around and everyone was trying to figure out what was going to happen, but watching it again I saw stuff I glossed over the first time.

To put it simply, my worst gripe is that characterization goes out the window. Makoto doesn't believe in his luck, except no, he does now. Nagito serves as a stress test to make sure hope can always shine thanks to exploiting his give-and-take luck, except no, now he tries to make everything easier for everyone with plot-based luck he doesn't even know about. Chisa has no consistent character, Munakata's a hypocrite, and Juzo has some of the only character development.

And do not get me started on how the plot of DR3 tears apart then dances on the pieces of any possibility of Junko ever being a competent or effective villain at any point in the franchise. She's now a laughingstock and it enrages me far too much.