Behavioral mostly. Had a small case but nothing major. Just prep your strengths, weaknesses, why RSM, etc. and you'll be fine. There were two rounds in total, one with a supervisor and one with a director and partner.
I applied through college or university. The process took 1+ week. I interviewed at RSM
Interview
Very quick turnaround. Had a phone interview with a recruiter by the end of the call received an invitation to interview on site. The interview on site was strictly behavioral and was more like a conversation than an interview. I enjoyed the conversations I had with managing directors and a partner.
Informal but allowed me to get a good understanding of the companies culture. Was able to speak with a wide array of employees in every field and many different positions from associate to managing partner. Allowed me to get a better understanding of the differences that middle market offers.