I’ve had one for about 4 years. I love it, not just for recording near misses and such but for capturing scenery that I miss as the driver. While driving if my wife sees something, like a grizzly bear at the side of the road while driving in Canada she can press a red button on the camera, and that 3 minute clip is saved.
Very easy to use, plugs into a cigarette lighter socket in the car so battery life is irrelevant really.
I was listening to a news quiz podcast a few weeks ago and there was a question about a news item I had missed. A car was involved in an accident and the driver gladly handed over his dash cam to prove his innocence. The police however looked at all the footage on the dash cam which showed him a couple of hours earlier pull up to a line of shops, leave the engine running and then rush out of the car with a baseball bat, smash a shop window, grab some swag and jump back in his car and drive off.