I don't like side mouse. My desk has waaaaay more friction then a touchpad, so I can imgine it being quite uncomfortable. I presume I'd also be using it as a mouse 90% of the time, and I reackon I'd find it less comfortable to push a mouse around directly underneath my wrist then with a standard mouse.
I love OrbMouse because of how powerful it looks. The amount of control it offers seems way more then the others.