Gameplay, Gameplay, GAMEPLAY, GAMEPLAY.
Hated it, couldn't stand it. DE's were an annoying Pokemon Ame or Tomamdachi simulator that wasn't fun. Flowmotion was basically freakin broken and no kids you can NOT turn flowmotion off. If you take all the abilities off then Sora just flowmotions and you can't control him.
The command deck system returned but even less varied than before which was not only boring due to it's appearance in so many games so far but, in conjunction with the keyblades growing pitiful damage in games, basically made me spam my commands over other tactics....or ya know even having tactics beyond "Balloonga, balloonga, cure, block".
Drop system, while easily enough bypassed, was still a pain in the ass if it caught you in the middle of a boss fight.
Still suffered from the multi scenario of BBS. While not as big it still made things repetitive as I did the same world freakin twice in one playthrough.
Did I mention how pitiful keyblade damage is or how it's gotten worse each handheld title?
Nightmares. Nice concept but I wasn't very fond of the enemy design. Granted some things have always been cartoonish but this was just to damn much. Like Splatoons leaked into the realm of sleep and painted more menacing enemies into what we got.