I've been fairly happy with the performance of my M$ Wireless IntelliMouse Explorer so far. Even under OS X, where scrolling works in most applications.
The main issue I'm having is with the buttons: sometimes I'm holding down the left button for an extended click, and the system suddenly reacts as if I'd let go and re-clicked. There are also times where the system won't respond to the scrolling of the wheel for a few "ticks."
Is this a common problem? I've heard the replacement rate on these is a bit high? Are people experiencing such problems with Kensington mice? I'm thinking of trying out a wireless optical by them...