ROI's interview process is very thorough, and for me, took place over a series of four rounds which were conducted over about a month's time.
Round 1: 15-20 minute phone interview. Very typical behavioral questions and briefly went over my former job experience. At the end of the interview, I was invited into the office for the next round.
Round 2: Started out with a brief tour of the office, which I thought was a nice touch but was just a bit awkward since you are asked to wear interview attire and the rest of the office was dressed casually. After the tour, you move on to what many consider to be the most polarizing part of the interview process which are the assessments. I was put into a conference room by myself and given a series of assessments, which includes 80 logic questions which you are given 60 minutes to complete. They varied from mathematical, to vocabulary, anagrams, patterns, etc. I really do believe ROI just wants to test what thinking style you respond best to and if that would properly correlate to the position you are under consideration for. After this, there are quick grammar and typing assessments.
Round 3: Short in-person interview. My interviewer was the same person from HR who performed my phone interview. It is basically a more expanded version of the phone interview, with more in-depth behavioral questions. It took about 20 minutes.
Round 4: Final in-person panel interview. I spoke with the same HR representative I had been speaking with for my first two interviews, the head of HR, and the head of the department I would be working under. The interview was very straight-forward, and all the questions were targeted at why I was interested in ROI, what I was looking for in a new position, and my work/educational background. No questions are targeted to catch you off guard, I found they were all straight forward and directed at truly gathering if my experience and personality were a good fit for the position for firm.
Overall, despite the interview process being longer than usual, I found it to be largely a positive experience, with everyone being friendly and responsive throughout.