I used to own the wired Mighty Mouse before but I was not satisfied with it. My major problem was the scroll ball which stopped working after a year of normal use and I just couldn't get it fixed. However, when it was new, I loved the scroll ball and I didn't want to downgrade to other mouses that had only the traditional scroll wheel.
After careful consideration I gave a try for the wireless version, hoping that it might have a different design. After all, I'm not sure whether it works differently inside, but for the time being it works flawlessly although it's almost a year old now. The only maintenance I regularly do is cleaning the ball with fiber free wet lens cleaner. It takes only a minute once every other month and the mouse works like a new one.
The battery lasts for months for me so it should not be a concern.
The weight of the mouse is just perfect and it glides without effort on my plastic desk cover.
The motion is accurate.
Well, the price is pretty high, but all in all I think it's worth it.