Applied online. First round consisted of the Problem Solving Test and two group interviews. The PST was tricky (be sure to do the practice tests on the website), but not impossible - just make sure you don't get yourself into time pressure. The two group interviews had different formats. In one, the interviewer singled people out to solve various parts of the case; in the other, we discussed the case questions as a group, and then one person (rotating) would present the group's conclusions. I think the only trick here is just to not disqualify yourself by being a jerk. Moved on to Round 2 a couple of weeks later. This round consisted of two ~50 minute interviews which were very structured - a quick resume question, a personal experience component where you tell a story, and a highly structured interviewer-led case. One of my two interviewers was very genial, and made the case an engaging and interactive process. However, the other interviewer seemed not to like me (or was in a bad mood), and stonewalled me throughout the case. Got a rejection call a few days later from the second interviewer, who was once again a bit awkward and condescending. Oh well - they make their interview process out to be a foolproof and scientific system, but in the end it's just the luck of the draw.