I am still getting used to it.  My natural grip doesn't seem to line up with all the buttons so I am trying to force myself to hold it how they designed it.  On the fly mouse sensitivity is nice and I am really noticing the 4000 dpi (or whatever.)  Probably because I have never owned a mouse worth over $20.
Plus, the buttons are a little stiff on the sides and I find it a little awkward to press one side and not hit the button on the other side (due to the squeeze).
I will get used to it and learn to love it I hope.