Pros
Some folks were great, a lot of folks were fine. The exposure to senior level meetings and decision making was truly valuable.
Cons
Naturally, the hours were bad, but presumably you know what you are signing up for. I had worked long hours before but it is much harder without the sense of teamwork, camaraderie, and gratitude from senior folks. A few people were genuinely malicious and there was no way to protect yourself from them and no recourse when you were mistreated. Before I started people told me that a lot of backstabbing goes on at Goldman. I didn't really know what that meant until a few weeks into my summer. Most people were smart enough, but they didn't seem to be anything exceptional. If anything, the experience gives you the sense that smartest guys on Wall Street really aren't that clever. The simplistic level of the financial analyses and the lack of thought that goes into the inputs to analyses was eye-opening.