The game is phenomenally fun, with cool characters, abilities, and synergies for days. Revolving events make it worth your while to stick around.
However, the game, especially with the addition of new characters, lacks some polish. You can filter your heroes, but you can’t save teams/rune loadouts. Doesn’t sound like a big deal until you want to mess around with different characters quickly, then your run is longer in just setting up your team than the actual fight. Also, the events aren’t balanced well. Some events are purely there to get you to spend money, others allow you to excel and actually earn rewards, but then some you don’t have any hope of even participating in. You can easily go from early game to mid game, and the grind to late game is actually well done imo. A lot of players feel like the devs don’t respond well to feedback, but many of them have played for years so it doesn’t seem to matter.
In the end, it’s fun, but you’ll notice the cracks fairly quickly. Spending money is not rewarded much at all, ironically, so don’t bother. Even if it seems like a good deal, you’ll eventually get up to an appreciable participation level where spending money makes next to 0 dent in your gameplay.