You get used to it. The left eye becomes trained to be favored whenever one looks, but they're still fiddly. Depth perception is by the environment, rather than true depth perception. That's how one-eyed people can drive.
I tried, but I couldn't get used to them. I even tried a couple of different mirrors. I am pretty severely myopic though so that may has something to do with it. There's a reason they don't let people like me be a pilot in the military. you get more distortion in your peripheral vision, your brain filters out a lot of it but things aren't always where you see and think they are.