I like GoPro HD so far. Drawbacks originally was the editing software, but I found Windows Movie Maker Live worked awesome with it. Other than that I think it's a perfect camera for rafting/kayaking. Since it's such a wide angle (170 degrees) it really doesn't need a viewfinder. You just point into general direction and start shooting.
GoPro is coming up with a detachable screen also ($50) that you can use to review your recordings.
I've been shooting waterproof video for about 4 years and GoPro is the best waterproof camera so far. It's really meant for one application, take video/pics from your helmet or some action vehicle (bike, kayak, raft, car, etc). It's not really meant to be a handheld family fun shooting camera. If you want an all around waterproof camera, look at other alternatives like Fuji or Canon.
Also, if you have some scuba gear, you can find my first GoPro at the bottom of Skull on Westwater