Pros
The management and teams are very respectful, friendly, and accommodating. You are given three months to go into deep learning when you start. There is no pressure placed on you to be instantly productive. Mistakes are reviewed in a blameless fashion. You can make mistakes and not be punished. They really just want you to grow. They are working with a lot of the best tools that will look good for your resume. Fantastic compensation and benefits. I only left because the work role just didn't fit me personally. I probably should have stayed longer and tried to find another role.
Cons
I'm not sure there are any cons for the company itself. Every company will have some people who don't match well personality-wise but I experienced very few people hard to work with. The engineering work is very technical and mongodb is a complex database. Be sure the work is what you want.