Three rounds of interviews, I got up to the second one. Both first ones were over Skype, the third would have been in person in their Boston Office. Both interviewers were extremely pleasant and easy to talk to. It was very conversational and comfortable. Even the email they sent back stating that I did not make the short list for the third round was extremely nice. Overall experience was pleasant and easy, I felt like I was talking to an old friend. When I didn't get it I was mostly upset that I wouldn't be able to work alongside the people I interviewed with.