As stated above, they can be good or bad. All depends on your expectations are, who is participating, and the general vibe of the group. Don’t expect porn stars. 99.99% of the participants will be normal, everyday people like you and I. Don’t expect wild, outrageous sex. Make sure you stay within bounds with the person you are having sex with. Go in with an open mind. If you are a couple lose the jealousy of your wife with another guy.
Wife and I have participated in many. I can rate them all 7s and better. Many have been with the same persons so there is familiarity.