Applied online and was contacted the next day for a phone interview. Had the phone interview two days later and a few days after that was invited to an onsite interview. They treat you really nicely as a candidate and are great with communicating. I spoke with a recruited a few days before the interview and she detailed the schedule for the interview day and was very clear and straightforward.
The day of the onsite consisted of 3 back-to-back interviews in the morning as others on here have said. I had a portfolio review and two interaction design exercises. The portfolio was 1:1 but the two exercises had an interviewer and a newer hire shadowing the process, so it got a little hectic with two people firing questions and ideas at me during the whiteboard exercises. The questions weren't extraordinarily difficult but I couldn't keep up with all the questions and iterations that they expected. Each of the interviews were fairly casual but still stressful nonetheless.
After the interviews, I went to lunch with a couple people from the team that hadn't interviewed and then did a tour of the design space. After that we did a demo of the product. After the demo, those who move forward are invited to do more interviews, but I didn't make the cut.
It was my first onsite design interview -- I wasn't prepared (mostly mentally) for the whiteboard exercises- I felt really scatterbrained and my wireframes were all over the place. They got back to me with feedback promptly- though I wish it were more in depth, it was clear that they take the hiring process seriously and thoughtfully.
Overall it was a good experience. The people LOVE the work they do and believe in the company's mission and culture. That was really motivating and awesome to see.