It was a mixture of formal and 'from the hip'. Initial phone screen with recruiter, then with the hiring manager. After those two, there was an on-site interview that took up about a half a day. Then there was a weird moment of "well we usually take candidates out to dinner and get to know you better, but we didn't plan that tonight. Let me see if I can find someone to take you out." Seemed too casual in some places and formal for not reason in others.