Looking for Opinions on Open Relationships

I’m seeking opinions on open relationships from people who have actually been involved in an open relationship. I’m mainly just curious as I’ve had discussions about them recently with more than one friend who is in one. I’m not in one and don’t believe I want to be in one, but the concept is intriguing and I’m curious as to how it works.

What I’d like to know (from people in or who have had an open relationship) is: How did you come to have that type or relationship and how long did it last? Was it your idea, your partner’s idea or was it mutual? What did it look like…did you have multiple “relationships” or just date other people besides your partner on occasion? What were the “rules”? What were some of the issues that came up and how did you work through them? What were some of the most positive things about it? Did it ever stop being open and transition to a one on one exclusive relationship? Would you do it again?

Of course, anyone who wishes can comment but I probably already know many of the reasons why people who have never had an open relationship wouldn’t want one. I’d really like to hear from those with first hand experience, as my friends seem reluctant to talk much about it (we’re not all that close and apparently, they’ve experienced a lot of judgement from others who found out).