The whole process took me through many stages, from online evaluation, to a 2 hour exam, to, finally, a 4 hour interview. The exams weren't extremely demanding or difficult, they didn't require any special preparation for it. The interview, however, was a whole different matter. I was interviewed by three different people and they basically went through my cv over and over, asking me for more examples on their "powers". They only her people to start at the bottom, so anyone with a CV that doesn't follow the norm (i.e. if you took a couple of gap years, changed degree, etc), they will dig into the details until they are fully satisfied with the answers.