Most people tend to hate Bastion when they see him on the enemy team. His turret mode hands out the most DPS of any regular attack in the entire game AND he can easily heal himself in only a few uninterrupted seconds. Nearly every damn game ends with a Play of the Game by Bastion and his turret mode.
However, this breakdown of how to properly play him also highlights his weaknesses when playing against him. For example, if Bastion's turret killed you and you know he's still in the same spot when you return then you already know how to get rid of him.
The proper player moves around the map like a sniper who knows their position is compromised after a few kills. You need to keep moving to keep the enemy team on their toes. Just check out the advice in the video to see what I'm talking about.