The mouse is beautiful, the buttons work pretty well and the scroll ball is great! But the mouse has a rather annoying design flaw:
You cannot lift the mouse while clicking!
Here's the problem: The mouse detects the button is pressed because you press the body of the mouse against the base of the mouse. When you lift the mouse, there's no longer pressure between the body and the base of the mouse. So our mighty mouse assumes you're no longer pressing the button.
There's somewhat of a work around for this... If you squeeze the mouse, the base does not drop and you can lift the mouse. But since squeezing the mouse brings up Exposé, things can get pretty weird...
This can be a real pain when you're trying to drag files from an end of the screen to another, or when you're trying to make a huge selection... it is one of those design vs. function options that I'm still not sure if Apple's done the right choice.