Phone screen with recruiter, then a few days later an on-site interview lasting about 3 hours.
Lots of people were in and out of the interview room to talk to me --- seemed like they weren't managing their schedules well. Some interviewers even got called out of the room by someone else, and then that person came in to take their place.. and got called out a minute later. Weird.
Overall the interviewers were pretty interesting, had varied backgrounds, and were the kinds of people I would like to work with.
First impression of the office was "meh", but the hiring manager said I would get a tour. They almost walked me out the door without a tour but I asked for it and they handed me off to one of the engineering directors for the tour. That was the best part -- I probably would not have accepted the offer had I not been taken on a tour with that person.
I very quickly received an offer -- the same day in fact.