A phone interview, followed by an onsite with three interviews - two coding and one design. The overall experience, even though I did not get an offer, was really good. I would particularly praise how friendly and understanding my recruiter was, and the overall culture seemed really friendly.
My former TA works there, and I got a call from the recruiter following his referral. That got me a phone interview, and I passed it. I went back home over the winter vacation, and planned my onsite in February. I fell sick multiple times, and the recruiters were really friendly in rescheduling the interviews. The onsite was a real nice experience too. I liked all the interviewers as they had a very friendly attitude. I would have enjoyed it more if they offered lunch (which they might have, as I have forgotten), but I liked the office and the overall attitude of the people there.
As per the interviews, the questions did not require much algorithmic skill, but relied heavily on the edge cases. I wasn't at my best that day, and generally sucked, so I realistically would not have gotten an offer. My greatest nemesis was probably the design interview, as I had practically no knowledge for design stuff. (I am a machine learning guy). Also, I would suggest they consider senior undergrads/master's people for machine learning positions too!
But overall, an awesome interview experience.