Well, graphics might look cool, but nothing else. Progress, map and quests in the game depends on the adventure rank... It would be ok, but I faced such "rank wall" almost immediately (just first day, can't make through 10 rank).
Yeah, you could reach it, but it takes all your effort to do so + your team would feel so much weak if you didn't collect specific heroes or use strategy from other people.
Summons just trash. This game have so big gallery with so much legendary heroes, but in best case scenario, you'll get 1-2 in one season...
Oh yeah, seasons - another mechanic with bad realization. You see, every 3 month your progress will be reset, which makes previous problems even more annoying. Levels, rank and other stuff just disappear, with low value in the end (sure, some things remain untouchable, but it's so little). If story stay +- the same, if some boring elements needed to do again and again, if most new heroes won't be accessible... Sorry, maybe I didn't read all info well, but it's just tiresome experience.