Clark White
Explorer
The biggest difference I see between the 2 (what I have) and the 3 to make me want to upgrade, is that the 3 comes with a flat lens. If you never use yours underwater this is meaningless, but as anyone who has tried to use their GoPro 1 or 2 underwater will understand, this is a huge improvement. With the round fisheye lens of the first two models, the focus is horribly off underwater (don't ask, the science of that confuses me, I would think focused is focused). You can get a flat lens to retro fit to the first two, but then you get some pretty nasty barrel? distortion in wide screen mode, which you do not with the round lens...and presumably not with the 3 and it's factory flat lens. Other then that we'll see how much of a real world difference there is in low light performance, and I don't see the 2.7 and 4k qualities being worth it for anything except a professional since most of us don't have the ability to play that resolution anyway. Besides, the battery life already sucks for travel stuff where it's on for an extended time.
Clark
Clark