The interview process consisted of two separate phone interviews, as well as a third round of in-person interviews at the office in Atlanta. All people were very pleasant and I got the overall impression that they want you to succeed.
After the second round of phone interviews, I was invited in for an afternoon long marathon interview, beginning with a one-on-one with a VP, followed by a case study (Excel and a corresponding PPT Presentation), which you're asked to present to two higher ups, in my case a Principal and Manager.
Although they seemed to be agreeing with my analysis and even shook my hand saying "great job!" after my presentation had concluded, I received an email at 9pm the same night letting me know that they will not move forward on my application. I then reached back out to the recruiter, asking for feedback as to what I could have done better/different, and all I was told was that I needed to "focus on the case study", which struck me as odd considering literally everyone agreed with me and offered nothing but praise for my responses to their questions.
My advice (if it's worth anything at this point) would be to be sure to focus the presentation on the solution the client should implement, not just on the problem and your assumptions on the models you're using to solve it. Again, may or may not be wise to follow this advice, but that's the only thing I can think of at this point.
Overall, the experience was positive, and I'm glad they did not leave me hanging for the usual 1-2 weeks after the interview to let me know next steps/offer/decline/etc. However, as many applicants on here have noted before me- the feedback to the applicant must improve, a generic "focus on the business case" is not constructive nor helpful in any way, and leaves the door open to speculation as to what the "true" reason for denial may have been.