They are great if you dont have any sort of camera or iphone.
I just bought a mount for my digital point and shoot camera that I already have that shoots HD video and has a bunch of functions like wind cut and has a LCD screen that the Go Pro does not have even though mine is a few years old.
If I was a surfer or mountain biker I'd get it due to its durability and water proof-ness but its just not needed for me to shoot automotive footage and would only make thing harder since it doesn't have a LCD screen to confirm the shot.
I just picked up the CruiseCam headrest mount for $40 and a suction cup mount.
http://www.cruisecam.com/products.html
Heck you can get the same results with a iphone and mount for shooting automotive videos.