You get to do hands-on work for clients and have more responsibility than you do at most internships. It really is a great resume booster for strategic communication, PR, and social media.
What I wish was different
It is an unpaid internship, and there isn't much opportunity to switch projects/tasks/clients if you do not like an account.
Advice
Let folks know when you really like an account, and they'll be sure to pull you into more projects and give you more responsibilities with that account.