Here's some truly nice footage shot with a GoPro HD.
You'll see a skilled paddler in smooth surf on an overcast day.
What I like about the footage is its modesty: no self-aggrandizing rock music or opening titles. Just good footage shot with a waterproof video camera mounted on the foredeck so you get a wide- angle view.
The one drawback of GoPros is their price: about $250 for an HD video camera that, while it shoots good footage, does little else. Crummy audio. Weird controls. Overpriced accessories.
GOPro's best competition is the Kodak Playsport ZX3.
The Playsport's drawback: it's not as durable as the GoPro. The GoPro case and camera are separate elements. The Playsport is all-in-one. Break the case on the Playsport and you broke the camera.