Given the harsh environment I subjected it to I am extremely impressed.

Over the time I've had it, it has held up well despite traveling in my briefcase frequently and being used in dirty environments

My previous Logitech mouse finally had to be retired because I just couldn't clean it satisfactorily enough anymore, but by that time it was three years old and was in a "dirty" environment

Depending on your environment (dust, food, etc.), the ball may need to be cleaned (increased force needed to move).

These style of mouse must be cleaned often around the track ball just the environment we all live

I work in a very dusty environment and these trackballs take quite a bit of abuse.

(I use them at work in dirty environments so after a while, the buttons gum

Even a few months later I still tense weirdly trying to use the mouse like a regular one

so i clean i out regularly