Really great Full HD camera as long there's a moderate amount of light around. Pretty useless during the Finnish winter. Waterproof and attachable to pretty much anywhere. Just as good for holidays as extreme sports.
I was given one of these for my birthday and I finally had a chance to use it on a kayaking trip. It took great high quality video under a very wide variety of lighting conditions ranging from facing into direct sunlight to looking into shadows. The lens is slightly fish-eyed lens so you don't have to worry about pointing it exactly in the right place to still capture what's going on.
reasonably cheap sports camera - great for scuba diving up to 180 feet, attaching to your skis or snowboard, or even to your car. These things are mostly indestructible, and the video and sound quality is awesome - the HD cameras have stunning image quality that is a joy to watch.