Installed this over the summer. Not really necessary, but I was always backing into trees and jacking up my rear fenders, so this helps. They're actually really cheap components, too. I think with the switch, the monitor, and the back-up camera I have about $40 into this. Fun project.
The monitor is suctioned onto the dash, so it can be removed easy enough for cleaning. I usually keep the pressure washer away from the dash anyway. Rear monitor lights up when on. Works pretty well. At night, you're not going to see long distances, but in the daylight it's pretty decent. Monitor does get static when going down the road at speeds, but it's tolerable. I need to get in the dash and do some better wiring, but for now, it's on a live power so I can switch it on without the key.