I liked the Magic Mouse when I saw it at my local Apple Store, so I took one home for my Mac Pro. It seemed to work for awhile, but now it is very erratic at tracking and speed, even when MouseZoom is installed. Its Bluetooth connection has dropped several times, and it either comes back after a long wait or simply fails to connect again.
When I moved back to my wired Apple mouse, I found that I had actually preferred the form factor of the Magic Mouse, and I missed the button-less scroll wheel.
The Magic Mouse seems to be working fine for many users, but there are some hints that the little rodents are having trouble with some older hardware. My 2006 Intel-based Mac Pro may be one of the computers at issue.
Apple will hopefully issue a software update, if that is the problem. In my case, the only magic I'm going to see from the Magic Mouse is when it disappears from my desktop.
How is it going for you?