There was an article by Bob Beech on this published by Commercial Motor a few years back.
Some older drivers who wear ‘distance’ glasses seem to struggle with the MirrorCam.
I can’t say I noticed a problem with it at all (and I’m quite old, with distance glasses), but I only drove the truck in daylight. Also, because I don’t drive a truck very often, I found it easier to adjust to than some folk who drive trucks more frequently.