Each interview consists of about half an hour of on-the-spot problem solving and half an hour of talking about one particular experience from the candidate's past. The problem solving is centered on one business case; you are asked a series of questions which tend to progress rather naturally. For example, if you suggest, "I would ask the CEO for figures for sales for the previous 5 years", the interviewer may hand you a sheet with exactly that table. Equally, if you find yourself in a cul-de-sac, or if the interviewer feels you're going down the wrong tack, the interviewer will guide you toward a possible approach.
The interview feels like a collaboration; I felt like I was role-playing being an employee during each interview. I asked questions, and didn't necessarily try to "have all the answers".
In the final interview, instead of talking about an experience from my past, the final half an hour was in fact a role-play exercise: I was briefed on a situation, and had to improvise for about 20 minutes while the interviewer played the part of another character described in the setup.
I liked the fact that each "interviewer" was an associate or partner from the company. I honestly felt more attracted to the company through my experiences with the interviewers. The HR people set up the interviews, but the interviews felt like a "real" test of my skills applicable to the job. There were no buIIshit interview questions like, "Why did you apply?", "What is your weakness?", "What is a leader, to you?", etc. It was just hands-on problem-solving, and test in how you present yourself. Are you respectable, confident, quick-thinking?