Honestly, I've been watching the Days stream a bit (no spoilers, don't worry) and I think it doesn't exactly work as a "movie." Whenever we see a battle that is supposed to take place after a cutscene, it just suddenly skips ahead to the aftermath and it just feels disjointed.
So, I wish we could have gotten some gameplay in Days, but only a very limited amount of gameplay and by very limited I mean only the boss fights that are represented in the cutscenes. Roxas would be fixed in every way, not at all customizable and, of course, given certain changes from boss to boss to represent the passing of time and him getting stronger. I think it would flow much better. The battles themselves wouldn't need to be a big deal since the point is just to have a more natural progression. I dunno. What do you guys think?