Alright, FedEx just dropped off my new mighty mouse about 20 minutes ago, and I absolutely love it. I'm not basing this on any reviews I've read, good or bad, this is my experience and mine alone.
1) It's very easy to slightly lift your index finger to execute a right-click. Upon a bit more examination, I've realized I did that anyways. Even with my previous MS 2-button mouse.
2) The scroll ball feels really cool, and isn't too squirrly, as I was afraid it would be. Can't figure out the diagonal scrolling thing, but then again I rarely even need horizontal scrolling, so why am I complaining.
3) The side buttons require 5 minutes of getting used to, they seem to squeeze a bit tough at first, but you soon figure out "how" to press them, and it's almost like the mouse reads your mind from then on.
4) Tracking is not a problem at all, seems just as precise as all other optical mice I've owned.
5) Gonna give it a test in WC3 and Diablo 2 pretty quick here, gotta do the dishes before my mom gets home, but I'll try to be back
Got any questions about the mouse, post em here and I'll see if I can answer them.