It's just way too slow. The rate at which you get points to spend on upgrade craters over time for some reason, they made it so you have to complete goals to get points. And every time you complete a goal, the next goal is higher. Two of the goals are set, just raising the number each time, and the third goal can be rerolled once per match with...maybe 5 or 6 things it can choose? Didn't really keep track. This third goal is the most renewable source of points, typically having goals that are more "do thing x times" rather than "get x points in one throw." The problem is that "once per match" part. Matches get LONG. Even with the game on the highest speed up value.
This is where the "slow" part comes in. The max speed up option is not NEARLY fast enough, and there's no option to forfeit a match, and they quickly become both longer and completely unwinnable. Your opponents will scale faster than you do, starting at league...6 or so? Somewhere around there. So you're stuck there, you got the third goal of "win 4 matches" or some bullshit which is the worst one, you reroll it and get "win 4 legs" or something like that. But like I said, matches are currently unwinnable, so you just have to wait for this match to end so you can reroll the 3rd goal again and hopefully get some points. The first two goals are irrelevant here because you've met them as many times as you practically can with your current stats. So you sit there and wait, and wait, and wait, and eventually you finally lose the match. Next match, reroll the third goal, and you get the one for..."hit 20 3 times in a row" or something like that, pretty doable with a decent number of upgrades! So you get it, it gives enough points to upgrade "horizontal accuracy" from 50 to 51 and "nerves" from 31 to 32 or something, and...the next goal is "win 4 sets". You just used your reroll for this match to get those points, so now you wait again. And you wait. And you wait. It's at this point that I stopped playing.
2/5 because I really like the concept of upgrading your darts skills until you hit the bullseye every time, but this game did not deliver on that end. It was fun at the start though, so I feel 2/5 is fair here. Give it a try if you're fine with bailing on it as soon as you start losing more matches than you win, that's the warning sign to get outta there if you respect your time.