Some of the most amazing footage is caught on GoPros. To wit: http://lilhub.com/you-won-t-be-able-to-stop-watching-this-over-240-incredible-hd-clips
(not all shot with GoPro, but you get the idea, the video starts getting really good at 0:57.)
However, GoPros have a very very high douchebag-to-quality ratio. For each epic-awesome GoPro clip I've seen, there have been an overwhelming number of noobs doing stupid things and generally in-my-way sporting a helmet camera.
Helmet cams do have a place. It's just not on the helmet of the average person.
I'm not gonna lie: I considered lending a helmet cam to Bradley "Honeybadger" White, just so I could figure out where the hell some of his really obscure adventure routes are located.
Also: get off my lawn. And back on topic.