Pros: I have always used Logitech trackman/balls for more than 20 years.
Cons: the one before this one lasted for at least 5 years. this one only lasted 6 months. the left click button eith double clicks or does not hold when you are dragging something. I used canned air but it did not solve the problem. I am very disappointed given I have been using Logitech trackman/balls for so long. And no I did not abuse it! I am a baby boomer with an IT background.
Pros: Great control and accuracy, once one gets used to the feel of it very hard to go back to a normal mouse.
Cons: The buttons wear out unusually fast. I have used this style of mouse for over 5 years or so and recently I have had to replace them much more rapidly than before. I use them for gaming and probably press the buttons more than an average computer user, but the mouse isn't even lasting 6 months anymore.
Summary: -Has a bit of a learning curve to get used to. Anyone who has ever used my computer always say the same thing: "I HATE this mouse!" but after a few days of use, you adapt and there's no going back to a "normal" mouse.
Pros: -Very ergonomic.
Cons: -If the ball gets the tiniest dent in it, the ball tends to "stick" on the little nylon pegs that support it.