Pros
Quality of people and environment. People are friendly and competent and they try to work smartly. The snacks are a nice touch. There is always something interesting technically going around. The company seems recession-resistent and has some momentum. Management is approachable and works with you instead of against you, for the most part. Not too much politics.
Cons
Typical startup lacks focus, tends to be reactive instead of proactive but that is changing. People are reassigned too often. Compensation is reasonable but could be higher. Being a security company, they emphasize best security practices which can go overboard in some cases.