Pretty robust, though I expect it varies depending on the team. Failed an interview the first time I applied, passed the second time. As a person with a non-finance and non-programming background, I had questions ranging from general knowledge to puzzles to project management to my extra-curricular interests in coding (some of them were pretty hard problems) and technology stocks. Interview process is fairly lengthy but they have a phone/on-campus screen and then only one SuperDay (final rounds) so it's not unfairly tiring. You get to meet a fair number of members of the hiring team in rotation, so there's a fair diversity. I believe that's pretty standard.