Seemed fairly straightforward: About a 1 hour technical phone screen with a Principal Consultant and after that I went through a 4 hour interview with 3 developers and 1 person from HR.
Each developer had a different amount of time working with the company: 6months, ~2years, 8 years.
The first developer asked me to finish a couple of function declarations to fit the tests they had pre-built.
The second developer asked me how I would design a user interface for both an administrator and user and how I would set up an api to handle the data.
The third developer asked me about how I would solve larger problems in a team setting.
The HR representative asked me about previous jobs and normal HR stuff.
It was all pretty enjoyable and easy going actually. All of the interviewers were nice people, everyone seemed very knowledgable about coding and excited to build cool applications.
I would say I had a very positive experience.