Spoiler ShowI think the execution of how they implemented the new features was awkward and silly:
Instead of patching the base game to just have this extra content occur in the main game itself, a la FM for Kh2, they created a really awkward secondary, and even third-ary, mode that plays you through an odd amalgamation of the normal ending +new stuff. It feels weird and can be hard to explain, and potentially easy to mess up amongst the save files, which is unfortunate.
The new scenes and battles/battle partners, for the most part, are actually really cool - though if you had just beat the game right before the DLC, it might feel a little frustrating to have to watch so many of the same cutscenes, just out of fear of skipping a new cutscene addition. Still, because the story sets up the explanation for why all of this is happening this way, its not like this implementation method in inherently nonsensical or pointless; it's just very weird and awkward compared to how we've seen things done previously.
I think with the Remind content and the patch updates to the gameplay, I like Kh3 a bit better then Kh2FM now, purely because of the better Disney world exploration and utilization, and now it basically has almost everything the Kh2FM had gameplay-wise.
I'm satisfied, though I know its far from perfect, and is especially frustrating from a story-perspective because at the end of Kh2FM we really didn't have many questions that needed answering - we knew Xehanort had more to him that we didn't know yet, the chambers, and we wanted to know who these dudes in keyblade armor were. Compared to now... Where there's more characters and story concepts that arn't resolved then there are ones that are. [/spoilers]