There are three interviews, the first one is just with the recruiter and is mostly about making sure you're a match for the company, not as much technical as it is socially. The second interview is very technical however. You talk about your interests and skills in a semi-casual way. There are also a fair amount of questions you will be asked about how you would solve certain issues or how to do certain actions (applicable to the job). If you're enthusiastic about your field, this interview is also quite a breeze and almost enjoyable. The third interview is in my opinion the hardest and least conventional of any job I've ever applied to, it's a problem solving exercise but it's in my opinion rather confusing. It's a hypothetical scenario and you have to find the issues both socially and technically with the proposition. It's not a problem solving scenario like other companies have, that will for example put you in front of a terminal, it's purely to figure out your thought process.