Interviews are generally with senior managers and directors early in the process. Very candid exchanges focused mostly on the personal and interpersonal rather than the technical (although this may be different for positions in IT, systems, and digital marketing). Purpose is rarely to make you slip up but instead to see how you interact with others--process can be pretty superficial at times but the culture of the company is very collegial which is partly a function of picking some very high-quality people. I can't speak to selection process at more junior levels since I met with the company as a recent MBA, my guess is that it's more cursory.