Outside of simply having opinions, some people voice their discomfort with general system mechanics (I may agree with some of it) being overtunned, people also complain about something outright ridiculous like "dwindling playerbase of less than 500 players" in a game with a crossplay, almost like they are expecting pool equal to street fighter or tekken, which would never happen in current competetive market without some miracle.
Some are still grieving vanilla versus players who keep insisting how the game got ruined or something (this one deserves entire different post to dissect all together). Sometimes it's about lack of certain features which a present in other games and so on and so on.
What needs to be noted is that this mixed result comes from 66% of 48 reviews being positive, which is relatively smaller poll size, so it can look more skewed.
But yeah, just like in anything else, there is something worth to criticise with this game too.