Six interviews, three rounds of two interviews each. It was one of the toughest and most challanging processes I went through. A couple of case interviews were really difficult, with a sky-high level of ambiguity and plenty of curveball questions being thrown at me. However, two cases were pretty simple and straight forward. The fit portion was not as long as in most consulting firms. My general feeling is that Bain cares more about your creativity, insights and communication rather than your case-answering and structuring skills.