I didn't do the program, but I did spend a summer of Penn working for the national institute of drug abuse and I loved it! I love Philly and upenn's campus is close to the subway so it is very easy to explore the city. the only heads up I would give is philly is very dangerous and there actually have been multiple murders on penn's campus but I think the last was in the late 90s. since then they have stepped up security majorly, but students still did get robbed the summer I was there, which was 2 summers ago. you just have to be street smart and not go out by yourself after dark, I mean occasionally I'd cross the street to the grocery store but no long walks to yourslf lol.
if you do go to philly make sure you EXPLORE. I worked in olde city so I got a chance to see the city but I knew people who never took the subway. you just have to be adventerous and get off at different stops-olde city, penn's landing, city hall, 69th street and make the most of your time there. I loved philly and would go back if I could.