Flatiron team was amazing throughout the process. From the very first call, I was given a lot of information about the team, culture, process and was quite excited about it from the outset. The interview process itself was 1 technical phone interview over video call followed by an onsite in NY headquarters. All the arrangements were made smoothly and I never had to worry about anything.
I felt I came close but could not pass through all interviews to be selected. However, the positive experience and vibe that I got from everyone I met and the headquarters was great and I would surely re-apply again. They operate independently from Roche so they have good resources to scale and still operate in a start-up like fashion.
A tip: You will generally have enough time for all your interviews so take few minutes more than normal to discuss about the approaches before trying to code or design anything. I think you want to be on same page as interviewer(s) as fast as possible to make sure you are solving in the desired direction. Otherwise, you might come up with something that may still work but it may not help you and you would regret not demonstrating your knowledge to the fullest. All the interviewers behave in a very friendly way so make sure you take advantage of this.