Very professional! I had several phone interviews with people early in the process, and we discussed everything from the industry to the challenges that need solving. After this we arranged an onsite interview. I was traveling down from Boston to NYC and they were very accommodating with the schedule, ensuring that everything was queued up and ready to go as soon as I arrived so that I could make the return trip that same day. The different sets of people I met were all engaging, enthusiastic, and excited about their work. We dove deep on technical things, cultural things, and I got a very consistent viewpoint from everyone I spoke to (which is always something I look for, inconsistencies!).