I just bought it a few days ago.
Here are my thoughts

Negative:
Recessed mouse 1 and 2 buttons
A bit small
A bit too low profile
The scroll wheel doesn't tilt left or right
mouse 4 and 5 are in a position I find almost impossible to use

Positives:
it has 12 mouse buttons on the side
The side buttons are very easy to access and are not easy to accidental click
Comes with very nice software to control lighting, speed etc...
You can assign any buttons to any key
You can assign any buttons to a macro that you create, including timed macros
The macros work without having to mess with ISBoxer
I put the mouse on a 3 ring binder (So it inclines it) and helps the mouse feel a bit better

The good news is that I'm still using it. I tried it for a day, stopped using it, then actually wanted to go back to it.