I was okay with it personally. I thought Deku being quirkless at the end was a nice bookend with the beginning of the series (Even then he can still basically be Iron Man if he wanted to). I also like him being a teacher at UA teaching future heroes, feels perfect for him.

Romance stuff could've been given a more satisfying payoff for people invested, especially between Deku and Ochaco because it was teased so heavily, but that's my only real complaint.

So yeah, the manga didn't go out on top with it's last arc compared with the rest of the series, but I'm still satisfied overall. The series had some great moments, and a final arc that stumbled a bit (But still solid imo) doesn't invalidate them.