Purchased this mouse for my wife and myself back in January of 2010 and from my everyday use, I have determined this mouse to be of average quality. The Good: The mouse is ergonomic, fits nicely in my hand, and I believe that the shape was designed to fit in either hand, which makes it nice for left-handed folks. The buttons are responses and give adequate tactile feedback. I despise a mouse where the button 'sticks' when depressed, thus have a slight lag before clicking back up - this mouse does not do this which is good. It's a laser mouse and so cursor movement is pretty accurate. There are no lags when waking the mouse from idleness which is also a plus. You can also customize the middle wheel to perform specific functions; I have it set so that I can go back or forward while browsing, and depressing the wheel closes the current window - very useful for power users because it increases efficiency when working on spreadsheets, or multitasking. The Bad: Wireless connectivity is semi-weak. If the receiver is too far or if there is something blocking the receiver then the mouse may not work because it is not picking up reception. I have two of these so I don't think it's due to a defective mouse. Also, the receiver is too big and obtrusive. It would have been nice if it had the micro receiver now common in most Logitech peripherals. Also, although it has a good design, the mouse itself looks boring and drab. May have been a nice touch if it had some cool blue or red neon accents just to give the mouse an edge of coolness. 6 out of 10 stars from me.