The early game, and the game in general, paces pretty slow. Tutorial takes a while.
There is no live PVP in this game. However, there is a 1v1 arena, a 3v3 arena and a Guild Battle. In all three of these, you fight other peoples' builds(or a turret), but not real-time.
PVE is just dungeon crawling, fighting some bosses, some co-op bosses.
You can auto most of this game if you continually grind and upgrade your heroes, but if you don't, better leave that auto off.
There is a pretty massive cash shop, but it only has things you can earn through grinding, no cash-exclusives.
Endgame is just trying to build the best teams and fighting other teams with it. Just a endless grind.
Overall, this game is a nice little time-sink. It's cute, easy to understand, and it's gacha; Who doesn't love trying to collect 80ish characters(most of which are unusably bad)?!