Pros
Where to begin... This is the culture for people who want to experience the upside of being in a start up without the concern for its future. Everyone here is technical, and I can have enthused discussions about technology with every level of this company. When the product you are building has engineers in mind, so too does the management. Saw a recent post about the CTO. In his defense I don't feel anything "cult like" here whatsoever. I challenge anyone to find a guy who is more approachable and involved in the company on so many levels. His vision of what should be done is an informed one, and more importantly it is one that shows real passion, he is at a desk coding with everyone else, not in a corner office glad handing. Personally, I appreciate that. I've never experienced a work environment that dealt with assimilation of new hires as seamlessly as MongoDB. I felt welcomed right away. Biggest Pro: The people here. "Word Class" just doesn't quite cover it.
Kontras
Like every company, MongoDB has some growing pains. It is a company growing extremely quickly and this sometimes means directional changes that can feel jarring or frustrating to employees. I experienced a bit of this myself. However, these changes are typically very transparent and seem to gravitate around a general theme of what is best for the employees and the future of this company. Having said that, I would not trade this occasional feeling for a larger environment with a less exciting trajectory.