It's a gacha game first and foremost. You'll be doing a lot of juggling with the gems and summoning things.
There's a semi-unique gameplay at the start, slide around to move your character, tap to attack but it's very janky and not very responcive at all. Once you beat a couple levels, the 2x speed and auto battle unlocks and makes the gameplay non-existant. The gameplay is designed around you using the autobattle, that is what it is designed around.
The game is also massive, I had to download like 3-4gb of additional data, and even then it kept downloading more bits and pieces here and there.
Into chapter 2 the grinding kicked in HARD, left the game running on my desk going through a level 20 times and even after all that and it eating my battery hard because there's no battery saving mode for auto playing, I still didn't have all the items I needed.
Small things too like collecting quest rewards, mission finish bonus rewards, etc are annoying as well. You get a notification like "hey you get this!" but then you need to go to another section to actually collect them which gives you 2 more popups to confirm. Auto optimisation is confusing as well, doesn't always put forward the best people/doesn't equip the best items. Things also don't level up in battle, they can only level up with levelling items which can be hard to bulk get meaning you've gotta grind them ontop of everything else.
Even if you enjoy gacha games, this one is a lot more idle and awkward then other gacha games, there's certainly better ones out there.