I was flown to their facility in Washington at the company's expense and overall it was a good experience.
I had a 30 min interview with the recruiter and then I had to present a project that I have done in the past to them(7 people in the audience). After the presentation, I had an hour tour of the facility and after the tour, I had another 30 min interview with my potential teammates lastly, I had the last interview with the Director Manager. They were all very nice to me during the interviews. very nice people.