I agree with most of what Rick TYler said....
Music being loud: especially the whistle signifying the end of a round. Ouchie.
Center goal scoring and competitiveness: agreed. During practice I didn't see any consistent center-goal scoring, though a lot of robots our improving (especially ours

).
Human Players: hard to score in corner goals - mostly for me because of bounce in the balls and the ramp going to the goal. I feel it worth it to hold onto the balls and let the robot score.
Robots tipping over: Yep. Ours tipped over also. Even some of the smaller robots (ours is maximum height) were tipping going onto the ramp.