I have the Contour Roam. I've used it for helmet cam footage, and strapped to my bicycle.
Easy user interface. Slide switch forward to start, back to stop. Beeps to confirm.
Laser to ensure level.
Good video quality for the price.
Rainproof out of the box.
Nice selection of mounts.
No way to change settings without some sort of host computer/phone/tablet.
Sound quality is terrible. May be just my unit. Gain all the way up, nearly inaudible.
Forgets the date & time fairly regularly. Again, may just be mine.
Very limited support (pretty sure they're effectively out of business.)
Switch comes on too easily. I have had hours of video of the inside of my pocket.
No way to remote power while recording without compromising waterproofing.
There are two main video modes: wide angle 720, and a narrower angle 1080. The helmet cam footage I took at 1080 narrow angle is essentially unusable. Way too shaky. Mounted to my bicycle frame in that mode for on-road use, it's fine. If there's going to be any shake, make sure it's on the wide-angle mode.
Use a piece of gaffer tape over the switch to prevent accidentally having it turn on.