The interview process consisted of a 30 minute technical interview, a code challenge that took a few hours, and a three-hour on-site interview. The on-site was four 45-minute interviews with six people ranging from software engineer to the CTO, and mostly consisted of questions about background and some technical questions, with a bit of whiteboarding.
Ultimately, I really appreciated that they respected my code challenge without requiring too much additional "proof" of my coding abilities beyond my ability to speak to my role on previous projects. I also felt that everyone that I spoke to was extremely honest about the pros and cons of working there, and despite declining the offer, it seems like an excellent place to work. My only complaint would be that I was definitely looking to move significantly faster than FastSpring was, and so I did have to push regularly on timeline--but the HR staff was very accommodating in working with my schedule.