I played with the mouse at a nearby bestbuy.
While I was not to review tracking/usage/ergonomics at a very stringent level, I found it to be a nice mouse. It fit nicely in my hand and the usage was great.
With that said, I was on sitting up high on a stool and not really in positioned to how I usually sit, i.e., ergonomics.
I was and am a little temped for this puppy. I'm not sure how compatible it is, with Linux and how much work it might be to get it to work, so I'll wait and see.
My 3.5 year old girls were able to use the mouse and it didn't trip them up too much. I think its probably not a wise idea to have a wireless peripherals with such young ones - they pick them up and put and play with them in another room. So if I get a new iMac, I'd probably replace the keyboard and mouse.
To bad apple doesn't offer this in a tailed version.
It'd probably work in Linux as a normal Bluetooth mouse but the multitouch features would be disabled without installation of drivers.