RSR's interview process is quite thorough. I met with most of the MD's and other Associates. The interviews are very fit-oriented.
By the end of the interview process, you should have a strong sense of your cultural fit. I believe this should be an important factor in deciding whether or not to accept an offer, as there are a lot of strong/big personalities at RSR Partners. Personally, I loved that about the firm - it made the work environment fun.