I got a Magic Mouse for Christmas, and I like it a lot better than I thought I would. When first hearing about it, I thought the Magic Mouse sounded amazing, like a combination of the best features of a mouse and a trackpad (yes, I'm addicted to two-finger scrolling) without the mechanical deficiencies of past mice. Then I began reading people's experiences, in particular, gripes about the lack of configurability of gestures provided by the Mouse preference pane.
But I got one anyway, if for no other reason than I had to see for myself. And I must say, I'm mighty impressed. The mouse works quite well for my purposes. I can use it on our leather couch with minimal tracking glitches. And in most respects it simply behaves like a normal, decent cordless mouse, which is extremely useful now that I'm all portable and junk.
But what really makes the Magic Mouse something special is that you can, in theory, make it behave however you want. And that theory becomes practice with the installation of a single piece of software: MagicPrefs (or the more configurable, but less user-friendly BetterTouchTool, which also allows you to configure your trackpad).
MagicPrefs allows you to configure your Magic Mouse with whatever multi-touch gestures you want. I really like the fact that it allows you to disable single-finger scrolling and replace it with two-finger scrolling on the Magic Mouse. This alone has reduced the huge number of accidental scrolls I've made and has allowed me to match the way I use the mouse and the trackpad.
With MagicPrefs I've also assigned Exposé to multi-finger clicks on my Magic Mouse, bringing back a missing feature of my old Mighty Mouse.
Out of the box I'm quite satisfied with my Magic Mouse. And multi-touch gestures make it possibly the coolest mouse I've ever used.