I REALLY REALLY HOPE YOU GUYS HEAR THIS COMMENT, ITS AN IMPORTANT ONE.
There are 2 things I can name that are seriously problematic and have a significantly bad negative effect on gameplay. They have been ongoing issues.
1) The box to close the shop when you are running back into action is TINY.
In order to be efficient in game, I view the shop to see how much gold I need to complete the next item Im most likely to purchase, or to help make decisions. Sometimes I will be standing just behind a turret glancing at a decision in the shop, only to see an enemy champ running up to kill me, but I CANT MOVE until I close the shop, and missclicking the TINY shop box to close it forces me to watch helplessly in the clutch moment when my champ just stands there and dies in what must look ridiculous to any viewers. I cant tell you how many teamfights its interrupted or deaths its caused because I miss the tiny tiny tiny tiny little box to close the shop.
Im probably not the only player that relies on closing the shop with the box in the upper right corner instead of the hotkey....
2) Swapping item placement in the inventory is OFTEN very very laggy or completely unresponsive.
Ive died many times because of the unresponsiveness of this. It just doesnt register sometimes. I move health potions position quickly as I run toward a fight, then fight it out, then hit the hotkey to chug a potion, then DIE because the potion never moved to the location I told it to move to. Or I move wards to an optimal hotkey location for me (number 1, thats where I put them) then try to drop them in place in the jungle as I am running across the map to help a teammate. But as I said often the items dont move when I commanded them to, so I have to do it 3-4 times, just standing in the jungle when my team needs me.