While that comparison between CGI Sora and Young Eraqus did help show just how impressive KH3's graphics will be, there are still things about the Eraqus model that aren't quite on the CG level yet. The biggest thing for me is the hair. Eraqus' hair (Xehanort's too) still looks a bit blocky and clay-like. Im sure the lighting engine isn't finished yet, but you can see a more natural lighting happening with Sora, namely in his skin and the reflections on his lips. Everything just looks more polished and natural with CG Sora, whereas Eraqus looks unfinished. But, he IS unfinished, so that's cool.
Because that shot of Eraqus is almost a year old now, and I'm sure the graphics have improved even further in the time between that. Hell, we saw in the Jump Festa trailer that the newest build of the game is looking really sharp. Still not perfect, but as they gradually build up the graphical engine and add more and more detail, the game is looking absolutely pristine. I just hope that weird digital clay/play-doh look goes away in the final product. The graphics of Street Fighter V (mainly the character models) bother me for that exact reason and KH3 is being made with that same technology, so hopefully KH3's characters don't look weird and shiny like Street Fighter V's characters.