Interview structure:
1) quick screening interview w/ HR
2) ~45 min interview w/ a regional manager/leader
3) 2-3 hour in person interview in Chicago w/ senior manager/leader + HR
IMO they are looking for 1) people skills, 2) work ethic, 3) ability to build technical competence
all questions were behavioral/conversational. overall it's a really easy interview if you can relax and just chat with them. make sure your personality and motivations align with consulting: long hours, lots of travel, high demands, client-focused, no "office" (work is at client sites or coffee shops)
Personal experience:
my experience was similar to some others on here. it's not the most organized outfit. I had several cancellations, but ultimately went through to the last stage. the people were super nice although the senior leadership are definitely sharks.