First-round was a Google Hangouts session with the accounts manager and VP of Finance. Very relaxed and conversational.
Second-round was a three hour long interview at their office in downtown Oakland, with each hour allocated to one of three interviewers. I spoke with the VP of Finance, the CEO, and the accounts manager. Given the smaller nature of the company, I believe the CEO interviews most (if not all) candidates.
The second-round interview process, though lengthy, was not grueling. The interviewers made me feel comfortable, and the interview was conversational at times, and more question-and-answer at others. I was asked questions on my background, previous experiences, and goals for the future. Other questions also sought to gauge my level of interest in the industry, as well as more cut-and-dry "Can you/do you know how to do _____?" A bulk of the interview process focused on gauging whether you're a fit for their company culture.
The interviewers were also very transparent about the company, how it functions, future outlook (both positive and negative aspects), benefits and compensation, etc.
Overall, I had a positive experience and got a good feel for the vibe/work environment.