Bought one in September 2013

- Great battery life. Changed once since bought 9 months ago
- No lagging detected when playing FPS or MOBA
- HEAVY!
- Software is easy to use
- The rubber area is comfortable as it is not slippery
- Cannot share the receiver with other Logitech devices (non-unifying receiver)

I just send the mouse back to warranty due to the middle scrolling button failed to work (need to push VERY hard to use)

Send back to the seller, bluerhinoit (which is an excellent seller by the way). He has send it back to Logitech for repairs. Not sure the timing of this though. I have a spare mouse to use, so I'm not in a hurry