The first interview was a phone interview. Primarily to assess my background and fitness for the job.
The second interview was with the person who would be my boss. It was somewhat relaxed atmosphere but he covered a lot of ground regarding my experience, my objectives, what the job would entail, asking how I respond in varying situations, etc.
The third interview was much more brief and more of an introduction to the company.
Overall, it was thorough and I was positive about the opportunity.