I was tired of my old laser mouse (logitech) not working correctly on a highly polished coffee table or the rough surface of a my couch, and wanted a something better for the TV hooked to the flat screen.This mouse is comfortable, accurate, and functional.Things i like:-Works well at a distance.. no annoying lag or stuttering (using it for HTPC)-standard rechargeable AA battery .. will be easy to replace when needed-3 year warranty- AC adapter is a standard USB outlet .. cant have too many of these!-fits my large handsThe only thing i'd really change is the cord used to recharge it. Its not a standard connector like a camera or a harmony remote, so it's one more cable to keep track of.  That's a pretty minor complaint and at least they included a nice case to store the USB outlet and cable in.:Edit:It looks like the usb cord is somewhat standardized because i just noticed it's the same as the blackberry tour!! Been using it for a couple of months now and still think it's the best mouse out there; well worth the price!! 

Question: Does have a extra button?
Answer: This mouse is comfortable