Pros
Amazing world-class colleagues. Great, open and transparent culture. People love technology and it is a great opportunity to learn not only about MongoDB, but about databases and distributed systems in general. Your colleagues have deep experience in various areas of software it is an amazing place to learn. The product is very promising, although it does have its shortcomings as it is still relatively early in its life cycle. Twice a week lunch orders from seamless and the fridge stocked with beer and food are awesome!
Cons
Workload can be overwhelming, but that is a good problem to have as the customer base is growing. Unlimited paid vacation sounds great but leads to burnout in practice as most people don't avail of it. Top heavy management structure. Too many VPs, directors and managers, compared to the number of rank and file employees. Disproportionate amount of politics for a company this size, probably due to the top-heavy management structure.