I see nothing inherently wrong with polygamy. The thing is, it is difficult to sustain and remain attentive to everyone's emotions, private times, financial issues, kid time...
A couple of years ago, someone in a different thread (same general forum) asked something similar, about if I would be willing to participate in a group marriage - seriously theoretical. I said, theoretically, maybe.
I was asked if I would be willing to be a third or fourth wife. I said, no, but I would need to know a LOT more about consenting to be a possible second wife.
Of course, any marriage that I would be willing to participate in would have to be run according to Torah law, in an Orthodox fashion. Therefore, LOTS and LOTS of questions would have to be answered to my satisfaction before even consenting to consider such a thing.
But is it good or bad? I would say that would be determined by the purpose and thought process behind why it was being done.
Short answer: I need more info to give a good answer.