Got the interview through on-campus recruiting. First-round consisted of a half-hour fit interview and a half-hour case interview. Case was pretty standard- how to launch a new drug. ZS gives you the packet of information for the case so you can follow along and have the data in front of you.
Second round was a full day in the office. Day began (late) with a "demonstration" of the work. To me, the work did not seem super interesting. This was followed by a 45 minute case that was significantly harder than the one in the first round. I was totally off my game and could tell it did not go well. The interviewer was pretty quiet and gave minimal feedback. The case was followed by a fit interview with the manager of the office. The questions were expected. The final interview was another case, but they give you 30 minutes to sit by yourself with the case packet and then have 15 minutes to present your findings to the interviewer. I was also asked to take 10 minutes at the end of the interview to makes slides about the case. The day ended with lunch with a current BA who went to my school. The 1:1 lunch was pretty awkward.
Overall, the experience was pretty grueling. The people were not overly friendly and the office was strangely silent at all times. I didn't get a great vibe and was not shocked when I didn't receive an offer.