I applied and did the Problem Solving Test. After this, I had the first round of interviews (2 interviews with different people), which had the same basic structure: a personal presentation and one or two questions about personal experiences; case study; time for questions. The thing you should know is that they go deep into everything you say. In my case, they just asked one personal question in each interview, but as you answer they do follow-up questions to understand the context of the situation and to assess your approach. The business case can be quite challenging, especially the Math part. You should be calm and take your time, and also you should be prepared to not stick with one motive to whatever happens in the case, they will always be questioning you for alternative motives.