Pros
First and foremost: very supportive bosses. I feel motivated to do good work here because it's a collaborative environment and work assigned to me is consistent with my skill level. I'm trusted to make decisions, despite only being a college student. They fully work with my hours, as I'm a student. The pay is generous for a college internship, and although I am the youngest one in the building, I'm never talked down to or dismissed. I have made friends with coworkers and higher-ups, and pretty much all my interactions in the workplace have been positive ones. I see the CTO and founder sometimes as I grab coffee, and I'm pretty sure he knows me by name, which is cool.
Cons
The reason I'm leaving: no real room in my specific field of interest to grow. I have learned useful information I can take with me into my career, but since it's still a small company, the type of design work I want to do here is saturated. If you can get a job doing what you like here though and you don't mind working at a startup, I would recommend. Also, note that my internship here only lasted about 4 months, so while I have had a very positive experience overall, I don't know what the long term experience is. For what it's worth, most of my coworkers seem happy.