I submitted my resume through my university career service. I was asked to an initial 30 minute case interview and to complete math, verbal, and personality assessments. The case was relatively straightforward - I made two small arithmetic errors (no calculator), but my interviewer just asked me to check my math and I caught them. Even with those slips, I was asked to a final round of interviews, which consisted of a 45 minute behavioral interview and two 45 minute case interviews. The behavioral interview was fine, but for some reason I panicked at the end of the first case and that sentiment carried on to my second case interview. My first caser was nice until I hit a mental road block, and then he became quite clearly exasperated. My second caser was clearly disinterested and periodically was on her phone. On one hand, it's disconcerting to have someone scrutinize you while you try to work out math problems, but the phone use was also disconcerting. They also provide you with calculators, but they were terrible and had sticky keys...I would bring your own 4 function or scientific calculator and ask to use that instead in the final round.
I was unsurprised when I received a call the following week saying that I wasn't a good fit. If I'd kept calm, I probably would have gotten the offer. The most important thing in their cases is to keep your math straight - I would suggest sorting the data they give you into tables and having a revenue and cost column for each different scenario within the business problem they give. I would also suggest writing out all the units, i.e. x amount of $/customer, number of hits/ad campaign, etc. My errors in the final cases were largely borne of being disorganized in my haste. From my impressions and other reviews, I don't think they weigh the behavioral interview much at all, so long as you come off relatively bearable. Anyway, it was a valuable learning experience, and I ended up with another great company shortly thereafter.