They generally do 3-4 one hour long interviews. Each hour is with a different interviewer. They will have the candidate in a room and have the interviewers take turns coming in. They are very welcoming and are not intimidating in my experience.

Was told (by the hiring contact) that the first round would be an informal chat with the department head regarding my history/ experience/ alignment with company values. On the day (with no warning) this turned into a 3 person panel technical interview, for which I was underprepared. The interviewers present were pleasant to deal with, but being blindsided (hopefully inadvertently- if on purpose, this is a sneaky thing to do) left a less than pleasant taste in my mouth. Make sure you get confirmation in writing about the interview format before the interview is conducted.