The game client is easily the worst part about the game.
Other things worth pointing out:
-The frequent occurrence of having to have the client close the zombie client process. (LoL is already running, close it?)
-The mouse box glitch once summoned onto the map. (you can only move your mouse in a region in the bottom right of the screen)
-When all players have finished loading the game, but have not yet summoned to the map, if you briefly disconnect and do not receive the message from the server to summon to the map, you get stuck at the loading screen while the game has already started and you're still waiting at the loading screen with everyone at 100%. This forces you to close the client, relog, reload, and then try to catch up the couple levels you might have missed.
-When all summoners have finished loading and the client closes the window to reveal the desktop for a few seconds, sometimes the game never comes back up, preventing users from summoning on the map, and having to confirm the client close, reopen, relog, etc etc.
edit: -If my client's session has expired and i am disconnected from the game, I am forced to do a relog, and when closing the client, the client tries to retrieve server data before it can close, but just hangs, forcing me to (surprise) open the game again, and close the previous process.
When these issues appear together, it prevents game players from getting/returning to the map in a timely manner and causes teammates to threaten you with reports.