I had one over the phone interview and then was invited to fly to Boston for the final round. Had 4 interviews in one day (each with a behavioral and case) and then a 'lunch and learn' to learn more about the company. The case questions were hard (required field expertise and technical scientific knowledge), but the behavioral were pretty standard. I did not like that I was being interviewed by very junior people (i.e people who had only been at the firm 3 months or so) and the more senior interviewers typed emails while I worked through the math of a case! Can't decide if overall most of the interviewers were just rude or if part of the process was being a little intimidating.