This game left nothing but terrible impressions on me.
First of all, The worst and most noticable flaw is the lack of freedom and player agency. If you try to do something different from the ALLMIGHTY METAGAME, you might, actually will, even get banned.
Secondly, it's the stalest and most repetitive competitive game I've ever played. Counter-Strike, Unreal Tournament, other competitive games had a ton of maps that changed gameplay, even if slightly. League of Legends (and it's grand-dad Dota by extension) plays always in the same map. Combined with enforced metagame, playing on the same map just increases repetition to unhealthy levels.
The other maps, aside from ARAM, which was genuinely more amusing than the main map, were even considered by the community as inside jokes. It doesn't help that games on the most popular (in practice it is the only) map are 40 minutes long in average. Even friends I played with and claimed to enjoy playing the game, were always hoping for 70% of the matches to end. Winning or losing changed nothing in personal enjoyment. When we were losing it was grey screen, run to action (painfully slowly, might I add) and try to fight back in unfair, bullshit situations.
When we were winning it was boring as well, felt like just clicking on folks and watch them die. I know that every videogame sounds silly when you describe them like that, but when you lose all levels of immersion and conveyance, all that remains is the clicking.
Thirdly, jukes and MOM GET THE CAMERA moments felt like nothing but really short bursts of happiness and I'm absolutely convinced that they only feel good because it's a break of all the monotony. It doesn't help how little presentation the game offers because even the most top elite skill plays just look like characters roaming around. There's no flash, and little substance to keep myself entertained.
And finally, there is a terrible, dreadful carrot on the stick mentality. When you start the game and the matches are terrible and boring with some low self-esteem smurf accounts destroying the game by winning or whining, and this is justified as "it's just low level, it'll get better." And then my friends said it would get better at level 30, but they complained about the SAME ISSUES I HAD IN MY LOW LEVEL MATCHES.
This is genuinely my most hated game of all time. There are worse games, but none give me a stronger feeling of disdain than this one. Dota 1 had an excuse, it was a mod, it was part of a much bigger ecosystem. League of Legends on the other hand has very little to stand on it's own. I don't get it, and what little I manage to get, I vehemently despise.
Score: 2.0 (Terrible!)