I really liked KH3 in terms of general gameplay and the Disney Worlds, but it had a lot of annoying aspects, namely the horrendous mini games and the sheer amount them with their bad controls (damn that melon and cherry flan games, frozen slider and the 100 or so mini games this game boasts). The battles were fun with new elements like keyblade form changes and attractions, but the flowmotion was toned down compared to 3D to the point that I never used it. Sora is also now able to run up walls, dash up to high places in a flash with shot lock and skydive. The game is much easier than any of the other KH games, so standard feels like beginner on previous games, but the story makes it very unwelcoming to all but those who have played at least KH1, 2 BbS and 3D. I would strongly recommend playing 1.5+2.5 before KH3.
The ending was disappointing, although the DLC made it slightly better but there was a lot of unexplained parts in it that did not make sense to me even after having played every KH game and having a general understanding of the story.