Informal, laid back, and was done by would-be coworkers rather than any managers. They emphasized great importance on choosing people who "fit their culture" as much as experience. I am not sure how to describe the "culture" there, but the department I was interviewing for were all in their late 20s early 30s. I am 43 years old and had at least 6 more years of experience than both of my interviewers. They were all pretty friendly and the office seemed peaceful. Pretty great product as well.