Pros
There are a lot of great things about Duo. All-in-all, I'd say the best thing about Duo is getting to work with great people willing to help you change the world for the better Working along side ex-Googlers and connecting with partners at companies like Facebook, Etsy, Yelp!, Eventbright, Basecamp, MIT, Stanford, etc. is a huge plus. As a Google Ventures company, Duo employees have the opportunity to make use of many Google resources, attend Google employee events, and to connect with other phenomenal Google Ventures company employees on a friendly informal basis. Aside from the above, the company culture is one of open communication and ad hoc interdepartmental collaboration. This is a strong pro for self-starter types interested in meeting challenges well beyond the typical 9-5 office job.
Cons
Working at Duo takes a lot of self-motivation, confidence, creativity, and (most importantly) interpersonal communication. If you're looking for a 9-5 where you can go relatively unnoticed, collect your check, and go home-- Duo is not the company for you. The organizational structure at Duo is in in constant flux. This stems from the corporate culture of ad hoc collaboration and adapter to change. While the culture has its benefits, it necessarily comes with a lack of clarity around who is responsible for what. For some personality types this could be considered a pro (ex. self-starters). If there's no clear responsible party for something, taking initiative is likely the best step.