Entire interview lasted about 2 weeks. It was one of the most pleasant interview experience I have had. Two phone calls + Four on-site interview with lunch in the middle. First two were coding on whiteboard, third was design, and last one was behavioral.
The coding questions were fair, the design and behavioral sessions showed that the company is looking for people who are not only capable but are also passionate about their product. So it's better to know the product well before walking in. They are also very serious about cultural fit.
Overall, interview process is structured and thorough. From my interactions with everyone there, they seem like an exciting startup with a supportive culture, so I debated really hard on whether or not to accept this offer, but in the end went with another, more so for personal reasons.