Ergonomically, this has stopped my wrist from hurting. It lifts your wrist up just enough. Very easy to get used to using. I use it without a mouse pad and it's still very responsive.

I can't speak for the extra buttons (DPI, fwd/bwd) as they don't work out of the box on a mac and I couldn't be bothered to manually map them. But they seem like they are in good spots.