Pros
MongoDB is a fast growing company, where ambitious engineers can make a big impact. The culture is pretty much engineering-driven, which means if you are an engineer, (to some extent) you can choose and work on the project you think will benefit customers/company/team the most. The company has been doing extremely well in growing customer base and expanding to many countries around the world. MongoDB (headquartered in NYC) has a Silicone Valley culture (rather than Wall Street culture), which is embraced by engineers. People wear casually and work from anywhere they like. The work-life balance is also great if you have family to take care of. Senior management team is very transparent, and employees always get the opportunity to ask them questions in all-hands meetings. Great compensation (base salary + RSU refresh) and great benefits. Unlike other companies which have unlimited PTO but nobody actually takes vacations, MongoDB employees do take days off as needed.
Cons
Reorganization pain due to fast growth, but it also means new opportunities always come up.