I loved that I was able to get a sense for the inner workings of Congress. You see how staffers work, how lobbyists come in, and how House and Senate committees run their meetings. You get the chance to hear a lot of important figures in Washington speak through the internship series program, and Sarbanes' office also lets you go to many committee hearings -- so you bump into many Senators and Representatives! Everyone in Sarbanes' office is nice and friendly.
What I wish was different
I wish the work was more substantive. I spent a lot of time categorizing incoming mail (electronic and physical) and answering the phone -- which is pretty standard in a congressional internship. I would have loved to do more policy work though. I was able to write a few memos for the staffers, which I enjoyed!
Be proactive! If you ask the staffers how you can help, they will find things for you to do, and that will let you learn much more!