So.. I bought one of these a couple of weeks back - primarily for the missus and her Oblivion quest. Know what? This thing works! The 'experience' on Oblivion is utterly perfect - it now plays like i'm on the PC and i've scored approximately 5000 wifey points in the process. Haven't had the chance to try other things but, wow, expensive but this is the most impressive console mouse combination i've tried period.
One thing I forgot to mention is you MUST own a WIRED '360 controller - this is used to plug into the dongle to bypass the consoles hardware validation check. Sorry if you missed this on their web site but I thought it wise to make this clear.