Initially, I thought the castle in the realm of darkness was home to some other dark overlord new to the KH universe but after a while, that's just 'The Castle of Dreams' (Cinderella) submerged in a pool of darkness which is cool to see.I figured at the part when Terra showed up in that part of the trailer, it's just memories of the world fluctuating as opposed to Aqua just hallucinating.
For the art direction, I can see the complaints. I heard some people are comparing its visuals to the pre-rendered 3D backgrounds you often see in games in the late 90s like Final Fantasy VII. I don't see that (yet?) in the footage of 0.2 and Back cover but I definitely can for this:
Some cool stuff all in all in 0.2 but I fear the gameplay will be the same as what we've played from KH2 combined with elements from other KH titles (BBS, 3D). As for Back Cover, I haven't touched the PC/Mobile games but I do know a finite amount of what's going on in it so watching the movie will be a treat.