I can see surprisingly well. In fact, the passenger side one is better than the standard mirror as the rollcage obscured most of the mirror whereas the DTM one is small enough to be seen in the gap between cage and A pillar.
I should have added that they aren't painted - just straight out of the box black plastic. They would probably look better painted, but I reckon it would be like putting lipstick on a cow. The car is a heap and shiny mirrors aren't going to make a lot of difference.