Accuratus Kyb Saturn

Excellent range and response. I use it for teaching in my classroom and the portibility this product offers is invaluable. Very happy bunny...

lightweight, small but not too small to be unusable, trackball is accurate and usable

not really "bad" but having the left and right mouse buttons means you need to hold in two hands to operate mouse - easy if on a desktop, harder if you're mobile. Like I say, not really bad.