The MX is the top-of-the-line wireless mouse from Logitech.
Pro Good battery life
Once fully charged the mouse lasts for several weeks of moderate use before requiring further charge. Users are notified through lights on the mouse itself, and systray notifications when the mouse is nearing the end of its charge (generally several days before).
Even after several years of use this appears to be the case.
The mouse uses one AA battery. A rechargeable NI-MH battery is included. The battery compartment is easily accessible, requiring no tools to assist.
Pro Logitech Unifying Receiver (Dongle)
The Logitech Unifying Receiver allows you to connect multiple (up to 6) devices through one single, small dongle. The dongle itself is made up mostly of the USB connector, meaning it's small and so stays out of the way, and is unlikely to be bent or broken if knocked.
Pro Useful extra buttons
Three programmable buttons are easily accessed by your thumb.
In addition to the Zoom, Forward and Back buttons depicted, the thumb rest has a button for switching between applications, the mouse wheel may be held to allow drag navigation, and the mouse button may be tilted left or right for horizontal scrolling.
All of these buttons can be configured per application via the bundled SetPoint software.
Con Occasional Fault
A commonly reported fault is that the mouse's main buttons occasionally cease to function, or double click when only a single click is intended.
However this is easily resolved by removing the batteries and pressing all of the buttons to allow the mouse's capacitors to discharge.