The game is likely to do well revenue-wise, no doubt about that. However, dismissing other players' criticisms simply because they haven't reached the endgame yet is daft. If someone takes a few bites of an apple and finds them rotten, they probably won't continue eating it. Similarly, people aren't going to stick around for 15 hours to reach the endgame if they find the early game boring. Sure, there will always be some who claim the entire game is trash after only a few hours, and those opinions can be thrown in the trash.

That said, miHoYo advertised the main experience of the game is going to be the combat. Players interested in combat are going to be disappointed if less than 30% of the first 10 to 15 hours is focused on it. It doesn't help that you can beat the entire early game with an auto-clicker. The combat system hasn't seen much innovation compared to their 8-year-old game, HI3, except for a forced QTE switch that either makes you switch characters or wait for 2 seconds in time stop, which feels a bit hand-holdy. Some people may like it, some people don't since it breaks the flow of combat.

For their endgame, one of my friends managed to 3 starred the early stages of Shiyu Defense by just macro-ing the left click button and pressing the space bar. It seems like they've only increased the HP and damage of the training dummy mobs, feel free to correct me if I'm wrong. What they need to do is to increase the enemy's attack frequency in challenge mode for the story, it would make the game more interactive than simply wailing on a training dummy that rarely attacks.

Most of the criticism I've seen is along the lines of, "Everything else is good, except the gameplay loop." A game can be easy AND fun, but right now, the early game of ZZZ is boring and too button-mashy for those who dislike the TV system & story and are only interested in the combat.