The interview process was a month-long process speaking with many different people. The overall experience was very professional, and the interviewers are nice and understanding. I went through a about five interviews.
The first two interviews were on the phone and the conversation was mainly what we were both looking for and questions about the company. From there, the interviews moved to interviewers in my department. It is with these interviews you need to prepare for. The third interview was meeting my manager and she asked basic interview questions. The fourth interview they test you on how you handle different situations. Be prepared for anything they throw at you. If you are an experienced designer then you will have no problem.
All in all, it was a very thorough process, but I enjoyed it because it felt like they care about who they hire. It said a lot about the standards of BCG.