I initially saw the job posting my university's website & was interested. I filled out a fairly detailed online application and got a phone call the following evening from the recruiter. She was direct & efficient, asking me a few straightforward questions like what applicable skills I had & why I was interested. After about 10 minutes of talking, she asked me to come in later in that week for a test.
She explained that the test wasn't really the kind you should prepare for & was more about seeing if the company & I were the right match.
I came for the test 2 days later & was kind of expecting to have an interview after that. Instead, I took the tests (grammar, IQ, & personality) and then left. The tests are certainly challenging, but it's best to think of them as a "try-out" for both parties. If you hate writing, analysis, critical thinking, & problem-solving, this is not the right job for you. If the tests discourage you or you just give up halfway when you hit a really tough one, that's probably a sign to the company that you may not flourish here.
After the tests, I got a call later that day to come in for an interview. The first interview was intimidating at first, since it was in a conference room with the recruiter I'd spoken with on the phone plus 5 managers from the company who were hiring. It became clear over the next hour or so though that they were doing it that way so that all the managers would have a chance to meet potential hires & that the best candidates got placed with the most fitting managers. They took notes as I spoke & left time for me to ask them questions at the end (I mainly asked about the hierarchy / how much of the work is independent, etc. I would definitely think about things you want to know about ROI before coming in for the first interview.
At the end of that interview, I was given a book & told to read it and come back for a second interview later that week. I read the book cover to cover and took notes. I also made sure that I could picture myself doing the things described in the book (i.e. doing the job) and liking it.
For the second interview, there were a few different managers but some familiar faces as well. The interview opened with them asking me what I found interesting, etc. about the book. I told them what I thought, & we launched into more questions. For me, I think my biggest hurdle with the job was simply not having a solid background in business and/or analysis in college. I was worried that would be the weakness that held me back from getting the job, but one great thing about this company is that it hires motivated individuals from any background with the knowledge that motivated individuals are teachable. One interviewer (now my manager) asked me about whether I would find analysis interesting. I told her that I enjoy analysis when I understand the connection between the numbers & their application. I have never been a math person, but that has not been an issue (though there has certainly been a learning curve with certain things).
After that interview, I felt pretty confident & also excited about the chance to work for ROI. I got a final callback, had yet another pretty in-depth interview, was offered the job, & came in again to sign papers, etc.
It's a thorough and kind of intense interview process, but it works. It's best to view it as a two-sided process that ensures that both parties would benefit from the hire.