I had the Hero 2 and sold it, scooped a hero 3 white as soon as they came out. The new form factor is great. It makes the old one look like a bulbous piece of junk. The white edition is essentially the same as a hero 2. Same specs and video modes. Wifi is a nice but the iPhone app, while it does work, is crummy. Poor UI, not easy to use one handed, and it's slow as hell. The buttons are way too small and there is tons of wasted screen space everywhere. It just plain sucks. For basic start/stopping of the camera it gets the job done.
Battery life is also still a weak point. You *might* get 2 hours recording if you're lucky and you'd better remember to turn the cam off while not recording. The camera buttons are more robust and it looks/feels better in all ways.
I think the white edition is a good value at 200 bucks. It shoots 1080p, but I usually use the 720p(60
or 30fps) simply because it looks fine and 1080p makes it a bitch to store or edit the clips because of their size and bitrate.
I haven't used other action cams but the goPro is widely considered the benchmark. I also haven't seen the silver/black editions in action but they had better be fawking amazing to justify the price.