The import lag that has been present since closed alpha.
Video showing said input lag recorded with my Mums phone. - Lowest possible settings +90fps local server with no bots.
I can count roughly +50ms ( I think, Plz correct me) between mouse movement and Gun movement. It makes aiming extremely difficult at anything past point blank.
If they could fix this I think I could happily play the game. Just makes it a bit weird ATM