First round was two 45-minute interviews. Both interviews were 90% cases and the rest chitchat. Both cases were pretty quantitative. The interviewers were fairly junior (1-2 years tenure). I heard back 2-3 days later. Final round was a 20-minute fit interview (why did you choose consulting, etc.) and two 45-minute case interviews. The fit interview was with a manager (~4 years tenure), and the cases were with very senior VPs. Again, both cases had a quantitative focus, though they were a little more free-flowing (no exhibits, for example, but a lot of estimation). I heard back about 3 days later. Everyone at BCG was friendly; I left with a very positive impression of the people and the culture.