I don't play high, and hate playing against those who do... it usually doesn't make them better, only not realize how much they suck.
This one guy played 21 against me high... I couldn't guard him. He was too quick for me though it had nothing to do with him being high. Maybe if he wasn't high though he wouldn't have thought he could have. Who knows. I asked him if he played better when he was high and he said hell no... but I think he plays high all the time and is full of crap.
For me, it's definitely an improvement in my offense. I still can't run for shit and in fact, I'd argue that my stamina is a tad bit worse when I'm high.
But I make shots I never would have made prior. I have a bad habit of following the ball with my eyes when I shoot. You're supposed to lock your eyes onto the rim when you shoot and keep them there. Just like in golf you're not supposed to look up at the ball when you hit it. It throws you off just enough.
When I'm high, every shot I take, my eyes lock on the rim. I never follow the ball. Even the shots I miss are more like in and out whereas before I was missing by a freakin mile.