Summary: I got 2 years of use out of this mouse but then again I only paied around 15 bucks shipped at the time. Its a basic mouse that is stylish but it doesnt make up for its inherent flaws in designs. Theres actually another model of Kensington mice that has a removable top where a usb cable coils out and you have the option of using a battery or power from your computer.
Pros: Its has a really low profile, Ive noticed that there was much less fatigue on my hand.
Cons: Way more faults than their are strengths. For one, the dongle is a bad design, I used this on my laptop and it was just obtrusive. The thinner plastic part eventually broke off. Another thing, I dont know if its indicative of the quality of the mouse but the battery cover is not level. Over a period of months it grinds against any surface and either accumulates crud or looses plastic. The mouse eventually died because left mouse click just stopped working one day.
Summary: I'm no mouse expert, but the Kensington Ci70 mouse is, as far as I'm concerned, unfussy (no irritating buttons); robust (mice have a hard life); and comfortable (not unimportant - it's your hand's second most useful function). Happiness.