GoPro cameras are good for what they are; basic POV cameras. POV cameras have ultra wide angle lenses by default, that's what makes them POV. Ultra wide angle lenses catch plenty of stray light and there is "fisheye" distortion, hard to get away from that with a 180° field of view.
Control of video and image settings is limited, that's why all the GoPro footage saturating the internet looks pretty much the same. Like most inexpensive cameras, good lighting makes for nice looking video and photos, poor lighting, not so much. GoPro pays for better quality video on YouTube and Vimeo. Using a GoPro as a dive camera in water deeper than 20' is not going to look that good because the water filters out some of the color spectrum(if you like photos and video that is all blue, no problem).
GoPro cameras are worth what you pay for them but a $100 point and shoot camera will probably take better video and photos, you pay for the whole "personal camera" deal. I've got a couple of them and use them all the time for kayaking and biking. One camera failed not long after I got it, GoPro replaced it. The LCD screen is nice but sucks the battery.
GoPro pretty much has the major market share for these types of cameras, but they are no longer the only player. There are more than a few GoPro competitors with just about the same quality and somewhat cheaper.