We played a "scenario" at a friend's farm. The scenario was a kid friendly test of some objects to be used for a scenario game later that year. The ground was an old pasture, and a little bit swampy. It was cool, but not cold.
The paint worked very well. I was surprised at how far one could shoot and still get a break. The impact was very low. While refereeing, I was shot a couple times in the head. There was enough impact to make you notice, but not the solid thump of getting hit by a 68 cal ball.
I think that 50 cal is an excellent way to introduce players, especially young and/or timid people, to paintball. My step daughter played 50 cal twice, and decided to make the jump to 68 cal.