This forum has been very helpful for my interview preparation. So to give something back, here is my interview experience with McK.
The entire process consisted of 3 stages: Problem-solving test (PST), first round interviews and final round interviews.
1. PST: It's an 1-hr test with around 26 MCQs based on 3 data sets. Candidates are required to compute without a calculator, and make inference from text and graphs. For me, time control was the most critical. I� spent too much time on the first data set and almost couldn't finish all the questions. So make sure you have a good grasp of time.
2. First round: There were 2 one-to-one interviews held on the same day. They had the same format, including some competency questions and a case study. The compentency questions were fairly standard but you do need to be familiar with your CV. The case study was led by the interviewer who asked guiding questions throughout the interview. Exhibits were handed to me after uncovering some key trends / making the correct hypothesis. The case interviews bore some similarity to the ones in Case in Point. Again, calculations were involved in the interview. Since calculators can't be used, those with good mental math skills would have an edge. If you aren't that confident about your mental math, don't be shy to use the pen and paper provided.
3. Final round: There were 3 one-to-one interviews in total, each on a different day. The interview format was the same as the first round. But the case interviews would be more difficult to prepare for, as they were quite different from the ones in Case in Point. I would recommend doing a quick research into the background of your interviewers. It'd be helpful to know their industry/practice focus and understand the business model of those industries.
Overall, McK gave me a good impression. The entire process lasted for about a month. I was informed of the result 1-2 days after each stage.
Hope this helps =) Happy Chinese New Year to all of you!