Win 8 stinks on my Macbook Pro. Win 8 doesn't work properly. Don't do it on a production machine. But wait there's much, much more! It has multiple catastophic issues (trackpad doesn't work, the login frequently fails to see the keyboard so you can't login, etc.)
Do not upgrade. You will regret it. I am about to reinstall win 7 from scratch. The upgrade cost is cheap but the reinstall time will be days of my time!