I got the magic mouse pretty much only because it's really low-profile, so it slips into a carrying case really easily, and, uh, it's got the Apple look as well (I happen to like their general design, and the way their gadgets match in appearance across product lines. Yes, I know that's a fairly dumb reason to buy something, but a mouse isn't terribly expensive even if there's an apple logo on it.)
It's no good for serious gaming; you can play Portal and some casual games with it and that's pretty much it since it doesn't handle both mouse buttons pressed at the same time (they're both in reality just one hardware button with right-click being emulated through the touch surface). Also, the mouse needs extra software emulation to handle middle button clicks. That's a bit crap methinks, but oh well...
At least it looks good.