1st round: Pretty standard consulting interview. 2 x 45-50 minutes. 2-3 fit questions, a 25 minute case and then a bit of time for questions at the end.
If you get a second round offer they will set you up with someone to discuss second round interviews. The format is explained and some tips for success are shared. You can also get feedback from your first round interviewers.
2nd round: a 45 minute chat with a senior level person (likely a partner), followed by a written case/presentation. You are given a problem, some case notes and 2 computers (one with a big Excel spreadsheet and one with Powerpoint) and have 2 hours and 15 minutes to prepare for a mock meeting/panel presentation. This seems like a lot of time - it isn't. You then present to the panel in a fairly informal setting in a conference room.
If they like you, you will receive an offer. If they just need to see a bit more, you may be extended a third interview. Otherwise, tough luck.
All in all, a good firm with awesome, genuine people and a great vibe around the office. Definitely committed to work-life balance, although no consulting job will have a 40 hour workweek.