First round phone interview with HR, second round phone interview with Sr. Account Manager on the team, both about 30 minutes each. Third round: 6 one-on-one interviews over the course of 3-3.5 hours, speaking with various members of the team. Not super difficult or tricky - they just want to get to know you as a person and worker, hear about your experience and how you've acted or reacted in previous work situations. Good opportunity to get a feel for the company culture and ask good questions.
Fourth round: in-person, 20-30 minute presentation to a few other members of team. It's essentially a little research project: they want to see your work ethic, how you present, how well you can answer questions and think on your feet.
I thought I did pretty great across the board for all of these rounds - I was a bit nervous during the presentation, but I was confident. About a week after my presentation, I was called by HR to say they loved me, but went with another candidate. I was really surprised, asked for specific feedback and was brushed off. I asked if there were other openings coming down the pipeline for which I could be considered, and the HR employee responded, "Um... well... not with this team... let me know if you see anything posted that you're interested in, though!" I followed up with her once or twice over the next few months when I saw more roles posted, but I was ignored.
Good interview experience, but super frustrating to go through 6 weeks and 4 pretty extensive rounds to ultimately not even be told why I didn't get it or how I could have improved.