I submitted my application through my school's on campus recruiting system and was contacted within 2 weeks. I had 2 back-to-back phone interviews, each lasted 45 minutes. They asked mostly behavioral questions related to common competencies of an HR professional or a participant in a leadership program (decision making, project management, communication with difficult people). I was toldby the recruiter who set up the interviews to expect behavioral and case interview questions, but they did not ask any case-style questions (thankfully). Both of the interviewers were very friendly and professional.

First round includes two 30-minute interviews, then if shortlisted, four 45-minute interviews. General interview atmosphere is quite relaxed and you may end up getting quite similar questions from each interviewer. But make sure your approach to those questions show different aspects of your qualifications and attributes. Also make sure to investigate thoroughly about the company and make sure to have up-to-date and intelligent questions ready since you will have a plenty of time for a Q&A time with interviewers.