Castro,
I've never used circle hooks for bass, but they're used a lot for tuna and albacore and stuff. The hookup ratio is pretty shitty, plus you don't get to swing on the fish, you just let the line pull tight. If you set the hook, it'll just pull the hook out of it's mouth. Not the best bassin hooks, but for other fish, the theory is that the fish gets hooked in the corner of the mouth almost everytime. This is good for toothy critters.
-Brian