I bought a Magic Mouse a couple of months ago. I'm still a fan of the size, weight and design. Again, the standard Apple wired mouse always seemed a little light to me. The Magic Mouse seems about twice its weight.
As predicted, I got used to the touch-sensitive scrolling pretty quickly. The (optional) momentum behind the scroll (whereby, if you flick the surface of the mouse, the scroll continues well past the end of your actual gesture) is awesome. Flick it hard enough, and dozens of pages of text will scroll by at a time. I still really miss the side buttons which I had hooked up to expose the Desktop.
Battery life is good: I'm still on the original pair of AA cells at seven weeks, and the mouse tells me there's just over 50% remaining.