This game was a lot easier than Birth by Sleep, and plays very similar, replaces the DLink thing with the new digimons thing. And brings back the ability to deflect attacks with your own attack, instead of having to use the block to deflect. I think that's a big upgrade. The Dlink system was kinda bad, whats the point of using a different command menu, when I already set up my own command menu that I already want to use. It was only good early on, because using Aqua gets you cura as Terra and Ventus early on. When you play as Aqua, there's no good Dlink to choose.
I would say Birth By Sleep is the hardest game since KH1, the series was only getting easier and easier with each entry until BBS, and then BBS was kinda really really really hard. DDD is in a good place with its difficulty, but I do think the flowmotion stuff, especially early on, is really really strong, and makes the game a bit boring. Plus it giving you the ability to move very very freely vertical and all, while really satisfying and fun, makes for way worse flow of the worlds. The maps feel a lot less like worlds to explore, and towns that you want to see, and more like really big fighting arenas. No paths to explore, just a big room for you to fight in, with one entrance and one exit. Makes DDD feel very linear.
I really don't know how to feel about this game. It's not bad, I think it improved on a lot, and its flaws aren't major. That's somehow not enough for me to say it's good though.
Now one thing I do want to complain about the series as a whole. The games all have such cool and unique magic and command menu stuff. But all of the final fights have the bosses immune to the more fun CC stuff. So you end up filling your command menu with Curaga, and a few melee attacks that move you out of danger. I get that they want to make the final fights not be easy, but it feels so bad not having the ability to do what you want, anti gravity does nothing, time stops do nothing. its a waste of menu space to bring them. So the final fights are just hitting them until they die, and trying not to die yourself, and healing when you have to.