The Logitech t620 Touch Mouse is an entirely touch-based computer mouse, like Microsoft's Touch Mouse or Apple's Magic Mouse. It allows you to use up to six gestures on the mouse's curved top, including scrolling, app switching, accessing the Windows 8 charms menu and start screen. See also: Logitech t620 Touch Mouse & t400 Zone Touch Mouse review: made for Windows 8.
Logitech's drivers must be downloaded to enable gestures on the Logitech t620 Touch Mouse – Windows 8 will do this automatically when the mouse is connected. It uses Logitech's wireless Unifying receiver, which supports up to six devices on the same adapter.
Like the Apple Magic Mouse, the Logitech t620 Touch Mouse is far too flat to be comfortable. It provides no palm support – not so much a design flaw as a necessity, as your fingers are meant to be gesturing all over the top.
A single button near the front of the Logitech t620 Touch Mouse detects clicks, with the touch surface determining whether they should be interpreted as the left or right button. This makes it impossible to hold down one mouse button while clicking another. In most 3D games this means you can't aim and shoot at the same time, and you need a different game or a new mouse. You might also have difficulty in some photo editing or CAD applications, which may use both mouse buttons simultaneously in a similar manner.
Do the gestures really help you navigate Windows 8? Hard to say. Personally I found that it was quicker and easier, on non-touchscreen PCs, to use a combination of the keyboard and ‘normal' mouse movements than any of the Logitech t620 Touch Mouse's gestures. Your mileage may vary, but I'd be shocked if this mouse revolutionises computing for anyone, or turns a bad Windows 8 experience into a good one.