I played air softing with a group of friends out on a series of rock formations we call the catacombs. It was a lot of fun. For the most part you are going to have to trust those you play with to be honest about taking their shots. Though the number of people saying that it really hurts surprises me, but then maybe it was because it I was wearing a jacket and jeans while playing, so I didn't have any exposed areas, or maybe my group was using different pellets, or both. Still, even with a jacket, you should be able to feel a pellet make contact. I will say this though, I have played paintball, and airsoft's impact is nothing compared to paintball, not even close. Paintballs usually leave welts.
I had alot of fun with both, so if you have a good group, by all means go for it.