The company portrays a laid-back easy going culture, but their interviews are just the opposite. The questions and format are very structured and the recruiters are looking for very specific answers.
Be well prepared and do your research on the company. One of the biggest detractors for me was that the interviewers were all male and the company has been struggling with balancing their employee mix. It appears to be an "all-boys club" atmosphere, so if you are female, try to self-monitor during your interview.