The interview process is long, but not as long as expected from reading other reviews. I cannot judge fairly because I planned to start working about a year after the first contact (and they agreed to that, and it was great), but I think that if I rushed things, it would have taken 2.5 months.
I got a first quick phone interview of about 45', where they asked small and easy general questions, and to code up some little problems. My impression is that if you are worried about this interview, you are not going to pass anyway.
After that, they asked me to come to the office, where I had 5 interviews of about 45', a lunch, and a tour of the office. Accomodation was great, and the process painless, and I enjoyed the questions. They were easier than expected, but I think you need to be quite precise in the answers to get an offer.