Smooth quick and challenging. No matter how much you prepare they have very smart questions that test your behaviour and cannot fake. I was on the loop at every step of the way. Dan told me at the end of the interview that I made it without having to wait which I loved. I always recommend you ask for feedback as this is one of the company values. If you want to throw them off their chair ask this in the first interview and follow up on the second interview showing the progress you made based on the advice they gave you.