I have 2 GoPro HD Hero 2's which I don't really use much anymore, as I replaced them with a Drift Ghost-S.
The Ghost-S is much better than the GoPro2 IMO. I find its low-light performance far superior, and love the fact I don't need to worry about carrying around/switching housings depending on weather. That said, I do use an external mic with it as I'm a motovlogger, and using the rear hatch necessary for that does make the camera non-waterproof. Haven't had any issues so far riding in relatively rainy days, but another guy I know fried his in a downpour, so I'd recommend keeping the waterproof hatch on during poor conditions.
Battery life is great too, I consistently get around 3 hours of recording time as opposed to about 2-2.5 on my GoPros; and I love the fact it has a built-in viewscreen and included remote. I picked up an LCD Backpac for the GoPro and never used it, mostly because I frequently forgot to turn it off on startup and found my camera dead 30 minutes later.
I mostly use one of the GoPros now as an on-bike dashcam of sorts. That said, they're still excellent cameras, but they're also 3 generations old now with the Hero 3, Hero 3+, and now Hero 4 series out, so it's nearly impossible to find batteries or housings for them in stores. Not looking forward to my batteries eventually dying, but I might just hardwire the power at that point.