Two phone interviews (recruiter and hiring manager), two sessions of onsite interviews: team member interview, team member lunch, hiring manager interview, culture interview, take home project review/discussion. They want to get to know you beyond your skills and experience: how do you deal with setbacks in your life and at work, what is your temperament, can you ask for help, and especially why do you do what you do? It's not "difficult", but it is exhaustive. Be yourself. The recruiters are incredibly nice and helpful. They kept me informed and prepared at every step along the way. I had a long gap between my final interview and offer, so they sent me a bottle of wine.