I was invited to 2 interviews, first one was about machine learning, statistics, computer science and deep learning. Second was about architecture, problem solving and team work. First interview was attended by 2 senior engineers, second was 1 senior engineer and 2 younger engineers. Overall friendly atmosphere, although i did perfect second interview, didn't get an offer which is strange, because you expect not to get invited to further interview. On first one i answered around 70% of the questions.