The slow intros of Persona 3&4 didn't really bother me. These are both 80 hour long story-heavy rpgs so I'm fine with them taking some time to set up eveything. But I do have one big issue with these games: the dungeons. The randomly generated, boring as fuck, tedious dungeons. I'm acually not sure which of them I hate more. Tartarus floors were much smaller so you could blast through them quickly, but there was waaaay more of them. TV world had more variety in its aesthetics and music, and the dungeons were more thematically connected to the story. But both were terribly boring to traverse though.
On a similar note, I think Kingdom Hearts 2 really dropped the ball when it comes to level design. KH1 got some complaints about clunky platforming and confusing levels, but KH2 instead of improveing those aspects cut them altogether. As a result, the worlds are linear, with no verticality, empty and less interactive.