Got mine in this morning and have been using it since. I immediately loaded the updated s/w from Kensington's site. Nice to be able to program buttons the way I like. In the few hours I have been using it, it has been interesting. I have to do a LOT of cutting, pasting and scrolling of large docs for work. Doing that with the trackball feel 10x harder than with my old mouse. Granted I have been using a mouse forever. It just feels a little awkward to hold the button down with my thumb while trying to highlight what I need to cut or copy with my fingers on the ball. The same with scrolling. I think the spinning ball may be a better idea on paper vs. heavy use like a scroll ring or scroll wheel. It is elegant in design, but not sure of long term use.
Since Buy is so generous with their 45 day returns it gives me plenty of time to try it out.
