Pros
Synack showed me how fun and rewarding it is to work in security, and I count this internship as the most valuable professional experience I've ever had. I had a fantastic group of mentors who fostered a great sense of camaraderie on our team, and I had a very high level of ownership over the work I did. Everyone I worked with was very patient, knowledgeable, and gave me tons of constructive feedback on my code. I felt like I always had real, meaningful work to do as an intern, and the code I shipped had a measurable impact on the core codebase. Synack is doing really great work and I think the company's leadership is doing a very good job directing the company's mission and goals. For physical perks, Synack's office is well-furnished and nicely designed, and we had free catered lunches every day, as well as a gamut of snacks and drinks in constant supply. The company also paid for my membership to the gym in the office complex, and we frequently had employees' dogs in the office, a more-than-welcome addition.
Cons
Not exactly company-specific, but moving to the Bay Area and finding short-term summer housing was difficult and pretty expensive. Having housing assistance, i.e. help finding a place to live, would have been much appreciated.