The stories being separate don't bug me. What is annoying is that they are all paced exactly the same. and the level walls are high enough that you're basically forced to get all the characters early so really I have no clue with what's going on by the end
I liked the demos, but in just those 3 hours it irked me how party members wouldn't interact with each other. That combined with a non-overarching story really made it a non-buy for me.
It obviously is a budget issue, but I feel they shouldn't have advertised the whole '8 stories, 8 characters' this aggressively as if it was meaningful in any way - no is not, it's literally what you get, 8 completely separate stories.
Some people will like that, I don't. Character interactionis what makes jrpgs fun imo.
The combat is great, though, and going super saiyajin blue is awesome.