I have one. Love the damn thing. Takes awesome video and still shots as well. The only thing is, you can't preview the picture taken or the video. The new version of the GoPro fixes that, but only if you are using the lcd bacpac or iphone/android app. I think that set up is better if you are trying to do a "remote" shot like placing your camera on the far bank and you are fishing in the middle of the river.
The mounting options for on person are on the head or on the chest. The chesty mount works great. Only thing is you see a lot of the rod and your hands, but you can adjust the mount to sit higher or lower on your body. The head mount works ok, but it will be quite a bit "bumpier" since your head will move around more than your body.
Here's a quick vid I made to tease a friend of mine since he's bailed on my last 3 requests to hit the river.
Select the higher 720 setting...for some reason, youtube like to keep it at 360.
You can also mount it on your net, on your rod, or on a stick and just stick it in the water and get some underwater shots. But remember, it's a wide angle lense so you've got to be pretty close to the fish.
If you want to just do photos, most cell phones these days are pretty good. Get good at the self stiff arm shot:
Or lean it up on a rock or use a gorillapod JOBY flexible camera tripods for DSLR/SLR cameras and point-and-shoots
In any case, the GoPro is a cool little camera device, but if you are planning on mainly doing stills, get a nice waterproof camera or use your cell phone.