I've got the helmet one for mountain biking, and picked up the suction mount to experiment with some on-car stuff - it's ridiculously fun, and some of the camera positions you can get are awesome. The suction mount is strong and never came off the car, even though I 'leashed' it to something with a cable just in case.
HD video quality is brilliant, it copes well with vibration (but not perfect) and the wide-angle lens gives a good impression of speed.
I'll try and stick up a raw vid or two when I get home tonight!