Pros
MongoDB definitely has built a very specific culture and it has permeated all areas of the organisation. Everyone here feels as though they are part of the bigger mission regardless of department and it shows in how they treat one another and the excitement in each office. NoSQL solutions have matured a lot in the past 2 years and now can compete/replace a lot of legacy systems/use cases. MongoDB leads this pack. Training is the best I've ever seen and they also invest a lot into each employee to be successful. If you are interviewing think hard if the culture is a good fit for you personally. Double if you are in sales or are customer facing in some facet.
Kontras
Company is growing at an incredible rate, there is a bit of chaos associated with it. A lot is expected.