5 rounds: behavioral, technical, take home case, in-person interview with a lead (in Chicago), in-person interview (in NYC) with CEO with lunch and coffee with other younger consultants.
The take-home case was difficult for me coming from a science background, but I had a lot of help from friends and since it was take home I could prepare. The other technical round was fine.
The final round with the CEO was odd. I have a chemistry PhD (like him) and at one point I was drawing my dissertation on the board. The other people in my interview day and the other current consultants though said they weren't asked anything technical. What I really did not appreciate was getting the rejection on Thanksgiving morning since I don't think it's automated (another person in my group got his rejection on a different day and you get a recruiting person to send information to you throughout the process).