Well, honestly its the best Apple mouse I've ever used...
that being said, I don't really like it that much, you need to lift your fingers to right-click, the scrollwheel gets dirty and stops scrolling, it doesn't track as well, I don't like the shape and dissasembly is a *****, plus the squeeze buttons are pointless and software is not too good.
Now I love my MX518 (Logitech) on the other hand, excellent tracking, built in hardware support for DPI change (no drivers and works on every platform!), very smooth and precise scrolling wheel, really useful side buttons (also work without drivers) and the best part of it all, its very comfortable, its like the mouse is made of gel and shapes to your hand, the materials use have a very nice feeling and grip, best mouse I have EVER used, period, many people bash it for the shape, size and paintjob and instantly like the Mighty Mouse better, however once they got the chance to actually use the mice... MX518 was the king
. Additionally for the people who will want to install it, SetPoint is downright the best input software I've ever used, it lets you change the DPI to whatever you want and have 5 modes to toggle between with the mouse, you can have any button do anything and its a very unobstrusive piece of software.
I love Logitech mice.