Pros
Duolingo aims to provide globally accessible and fun education, and working at Duolingo is definitely fun and rewarding! The people here are all dedicated to the mission and really value top quality engineering and design. It's incredibly satisfying to contribute to such a wonderful product used by so many people around the world. The people at Duolingo are really top-notch, polite and respectful, while still willing to give and receive concrete feedback on the work in order to provide the best experience possible for our users. One unique thing about Duolingo compared to other jobs I've had is the level of impact, not just in terms of users but the breadth on contributions. Even as an engineer I get a chance to be fully involved in the ideation of my team's projects, evaluation of metrics, and triage of user facing issues. Putting on so many different hats is common here and really allows me to feel a strong sense of ownership and pride in my work.
Cons
Things can move pretty quick! There's a lot of momentum around launching new features and gathering engagement and learning metrics as early as possible. Teams are reorganized pretty frequently so you need to be ready for change.