The interview is very informal, but they try to catch you off guard with many of the questions. They're mostly looking for ideological alignment and whether or not you're "interesting." Try to be honest, friendly, and don't hide your personality. They're looking for people who will speak their mind, ask questions, and contribute positively to the culture. Strata has a very open culture, and people become friends very quickly. You spend a lot of time together--so they're looking to see if you're the type of person they want to spend time with in addition to your skills and potential.