I think it depends on the individual, and i dont want to stress you out by describing my own anxiety about it, but i thought the mmi was preposterous. The interviewers seemed like they were advised not to express any approval or disapproval, but they took it to some weird extremes. One of the people was very rude to me before i even started talking, and another interviewer was layed back in a reclining chair with her eyes closed and arms stretched out like she was barely awake. Also, some of the questions they asked were very tangentially related to the mmi prompt. I dont think im allowed to quote the exact prompts but in a simple non-medical ethical dilemma prompt (like a retail store return without a receipt) one of the questions was "what kind of coping skills would you use to handle the stess of this?" like really? If a retail return stresses me out i probably shouldnt be applying to medical school. Anyway, the traditional interviews were much more relaxed and the interviewers clearly knew my application very well. They did, however, ask more standard ethical dillemma questions, so the whole interview day was roughly 70% mmi-type questions and only 30% getting to know you/your experiences.