I quite like Microsoft hardware (natural keyboards, xbox 360 controller for windows, etc), but I bought the Natural Wireless Desktop 7000 recently and was very disappointed with the mouses tracking compared to my old Logitech MX 1000. In fact compared to anything it's terrible, it's jittery, has slow tracking, poor wireless range, and is generally worse than a R100 Microsoft Intellimouse. A disaster.
If this though acts anywhere near the claims MS is making for it, I may be tempted to give it a try after seeing some reviews. Can't see any mention of it being out in the US yet so can't imagine it will be in SA this week.