In all honesty they don't sound that great, mainly because often the guys are just anonymous and pushed off to the side afterwards. Standing around with a bunch of other guys in a small room, making small talk waiting for your turn doesn't sound like a fun experience to me, (this is where being bisexual would be handy

).
It might be great for the woman, since she is the focus of attention.
To organise one in real life would probably be a tad difficult due to trust issues etc. There is always one prick, (not in a good sense), who will try to not use a condom, or want to do something the lady doesn't want done to her, which I imagine would ruin the atmosphere.
If it was a party with enough women and maybe one woman was the centre of attention it would sound OK. You could have a poke, swap out, watch/chat/fondle with someone else for a bit and be entertained. I would be interested as an observer, but don't forget, any film you watch has all the dull bits edited out.
If you see some of the more amateur productions, they can have their own magic when it works, but there are a few where you see the woman frustrated because the rhythm of the sex keeps getting broken, or some guy isn't fully erect, or that one guy who keeps pushing through the group so he can squeeze the christ out of her tits. I've even seen one where a cute girl threw her hands up in despair because no one wanted to come forward first!
OK, I've seen too many movies of them...
For me at least, it's possible it could be a fun experience, but not necessarily an erotic one.