After a phone screen, I had an onsite interview with 1 person, which went well. I was then scheduled to come back and interview with 2 other people and do a challenge presentation. The challenge questions were confusing and, based on my feedback after the presentation, downright misleading in terms of what they were looking for. My advice is to call the recruiter and have him/her walk you through the expectations in detail. If you're not willing to spend 15 hours on this, don't bother. Actual questions in the interview were average difficulty and appropriate. The "Challenge" feels arbitrary and doesn't take into account that candidates may have full-time jobs in addition to interviewing at Medallia.