I have one of the older black editions and its been great. I also have an old 808 spy cam (found as a result of one of tech moan's vids) and that too was brilliant. The go pro was 10 x the price, but the spy cam was easily attached to a helmet via velcro.
My mrs is a photographer and a few years back she upgraded her 450d and bough a canon 7d. We though the quality was amazing, then last year she bought a 5dM4 and the quality is significantly better. You just don't know "good" until you see it, then you can't go back.
GoPros are good, reliable and the image processing seems to be way better than you'd expect given the sensor size.