I think I would just buy a couple more Hero 2s when they drop in price (hopefully). I don't think I would take advantage of the new features of the Hero 3 for my type of fishing.
The idea of 1080p at 60fps, then dialing it down to slow motion just seems uber cool. Their promo video on the home page of the GoPro site is just mind bendingly awesome. It makes me want to go fishing right now :)
Can't wait till this winter when Nico and I get out in some tournaments in bad weather with the camera running. I wish to heck I had footage of 2 years ago in the ABA TOC at clear lake when the weather turned ugly on day 2. I want the audio of the boat getting totally airborne }( and just blasting over big waves. Ha.