Zestiria felt like the team was experimenting with a bunch of new ideas and only a handful worked. They tried to do open world, which was an improvement on what we got with the Xillias, but they either didn't have the budget/time for putting anything interesting in the open world, or just didn't bother. The Skill system is interesting, but the game does a halfass job at explaining it, and you're going to have to grind your ass off to get any good equipment. The combat is fun, even if it's a step down from Graces, which I assume was the inspiration for the combat. The introduction of the arts, casting arts, normal attack triangle was actually pretty good, well once you set your party to quit attacking casters with art attacks. This also helped balance Armatization so that it wasn't completely overpowered, since casters would just obliterate you since you have no normal attacks in Armatization mode. The limit of skits to just inns and resting points was odd, and the steady removal of cooking is just stupid. Xillia 1&2 only had snacks you could buy at stores, and food can only be bought at inns. Who in management decided that cooking should be removed from the games? It's so stupid.
The story is fine from what I've played, though some choices the writers made really hurt it. Side quests really love killing off kids, but it's not necessarily a bad thing. Characters are fine, which a majority of the cast being fun. The only ones I didn't like were Alisha for being boring as hell and Rose for story reasons. Doesn't help that certain reveals towards the end fall flat since it relates to a character that's barely in the game.
Could write more, but at the end of the day, Zestiria tried a bunch of new things, but it ended up hurting the game in the long run for me. So, if Namco takes everything they learned from Zestiria to make this game better, we could have a really great Tales of game. Just please be good.