If you are playing single player, or casual online shadows add that extra bit of detail I personally like to see. However, in competitive, or intense online its better off for the precision, and clarity. For example, I play SC2 on ultra settings maxed out because it is a very graphically detailed game, but pro players who are on computers 4x as expensive and powerful as mine play on low to medium. Shadows, unnecessary particles, ragdolls, etc, all get in the way to them. Theres a difference between a platinum player vs a Grandmaster.