Pros - You meet different types of people, learn from others, new perspectives, and better understanding of people and the world, improved social skills, enjoying the company of others who are similar or different, and expanding interests, social dynamics are supportive and welcoming of differences, friendly, positive social experiences
Cons - Dominance, arrogance, too much blending in to get along, pressure to stand out or conform, judgments or prejudice, no openness, dismissal of views or ideas that are not liked or supported, the belief that the ultimate goal is to be liked by everyone, social awkwardness, limited respect for individual differences, social dynamics are oppressive rather than supportive.
Edit: I think some of the cons can be resolved, but not all. We are an ego based world, and unfortunately, we focus more on having our say and getting our way and often see this as incompatible with other people's rights or views. So, since so many things are always at odds, I think it's tough to expect paradise or utopia, but maybe with a little extra effort on our part, we can be learn to be more receptive and understanding of everyone's differences, and be more willing to accommodate, then life could be easier for everyone. However, as long as everything is a fight to be right or win, and not compromise, then we'll likely keep having the same issues we've always had,