There were 3 interviews total. Each interview was with someone new and had some repeat questions, but they weren't difficult to answer. The process was especially quick at the store I interviewed at. The 3 interviews were 3 days in a row.
Applied online and had one in person interview with the captain. It lasted maybe 10 minutes. Got a call a week or so later that I got the job. Very fast process.
It's two to three interviews, the final with the Captain (or highest manager) of the store. The interviews are largely to get to know your personality and how well you would do at customer service.
The interview process was absolutely wonderful! I didn't feel stressed or nervous and it felt like I was just chatting with a friend! Trader Joes is a great company and the interview was great.