Vantaggi
It's potentially a chance to practice some new skill, and you may meet some interesting clients. The people I worked with were generally nice. It was an insightful look into some behind-the-scenes of a lot of the marketing.
Svantaggi
In my time there as an intern I was overworked, unpaid, and entirely unappreciated. The second I was gone they wanted nothing more to do with me. Half the employees were unpaid interns handling nearly all of the social media for clients. I will echo previous comments that the entire setup was unethical and questionably legal. Management spouts a lot of empty promises, and seems incapable of turning off the marketing talk to actually speak seriously.
Management also took on far more clients then they could handle, and when confronted with the issue simply revealed they had no interest in actually making a long-lasting sustainable business. I tried to do good work, but management only wanted the bare minimum until the clients complained.
The obvious astroturfing on this Glassdoor page is disgusting, and what pushed me to finally say something.