I've been using this mouse for quite some time now, and have carried it around in my bag, pocket, and car. This thing just keeps on going. Other portable mice I've seen fall apart after weeks or days of use. I've gamed, used it for business and my newborn daughter has abused it, my dog has chewed it and it still works great (does have some teeth marks though). Performance It's been beaten up and battered and keeps working and the battery life is great. I use rechargable batteries for it, and end up recharging them about every 4 months. Durability I can't think of a type of punishment an average mouse could stand up to that this one wouldn't laugh at. I'd seriously be willing to let this mouse be Danger Mouse's replacement when he makes the decision to retire. Design Comfortable, small enough to travel with, but large enough for my bear paws. I like that the dongle (RF receiver) can be placed inside for easy storage vs the ones that have a little clip or area for it to sit outside the mouse. I've lost too many dongles that way. Comfort Small for travel, large enough for hardcore large man hands. The grippy texture on the sides is nice and comfortable. I mean it could have a little more grip, you know for when someone has to take it outside in a sleet storm or something crazy.