Bear with them -- it is a *lengthy* process, which has its own pros and cons. On the plus side, I really felt like I got to know the company and the team well. I met more people, which meant more familiar faces on day one. I also had more chances to ask questions and research the company, which I strongly recommend. I felt like the team -- especially the recruiter and hiring manager -- wanted me to be there and wanted to make sure I'd be happy in my role. Now that I'm in the door, I really see that the long process helps to preserve a truly amazing company culture.
Cons: honestly, the interview process at any company can wreak havoc on your self-esteem. More interviews mean more chances of being caught on a bad day, and obviously, a significant time investment from all parties. It wasn't fun telling friends and family "yeah...I'm STILL interviewing for that job." It may be especially nervewracking if you are interviewing at many places and perhaps delaying a response on another offer (not my situation, but I can see it being frustrating for some).