I think there's a thread around here about the differences between poly & mono?
To me the benefits FAR out weigh the negatives in a poly relationship.
I'm free to see other people within the boundaries we have set up. Not all of these relationships are, or even need to be, sexual. They can be platonic, romantic, sexual, intellectual, cuddly, whatever our needs are really.
There's more communication with my poly relationships than there EVER was with my monogamous relationship.
Compersion. I'm happier when they're happy & they're happier when I'm happy so it's a win/win situation.
There are as many ways to do polyamory as there are people practicing it!