To start with, the battle system is broken. One time it began waiting for an enemy to move after it had already died, and another I managed to get the final red slime's health down to (I believe) zero points, but instead of dying it started bouncing around the battlefield; both of which forced me to reset.
The combat system is quite interesting, but probably needs to be rebalanced. The enemies are too strong; that first battle takes far too long, and would probably be able to pass as a boss fight if you buffed their attack slightly; and due to some other things such as how the rotations currently work (which really bugs me, but I have no idea how to put it across other than just a 'lack of polish,' which isn't very helpful, I know), and the speed (which is fine as it is, but a x2 option would work wonders), it doesn't take long to start getting tedious.
As for something a bit smaller, the text on some skills bugged out (such as the effect text repeating over and over and names/descriptions being too big and overlapping or going out of the box. I can only confirm these for Coco for now, although I might search for more later).
But despite what I've said, it's pretty enjoyable, albeit a bit empty (for now). As much as the battle system frustrated me at some points, it's a cool concept and, with a bit of tweaking, could end up being really fun. A lot the nicknames and skill names gave me a chuckle and I really liked the gacha animation.