I was told the opposite by my college's pre-med advisor when I was applying. Her opinion was that what's really meant by "tell me about yourself" is actually "tell me what you're doing sitting in front of me right now." I.e., the interviewer wants to know, briefly, why you're applying to medical school and why you're applying there. My answer to this question was along the lines of "I'm a senior at XYZ university, where I'm a chemistry major and where one of my ECs is working as an EMT on campus. Working as an EMT helped me realize that I wanted to go into medicine. Knowing that, I decided to apply to ABC med school because of ___ program that you offer and because of its reputation." If the interviewer wants to know about hobbies and such, they'll ask (and they usually do, at least in my experience). If I was the interviewer, I don't think that the first thing I'd want to know about someone is their favorite color or that they like to ice skate- I'd rather have a background to add it to. And as an applicant, I'd think that, given the idea that first impressions last, I'd rather have someone remember me as the person who was grounded and confident in their decision to be a doctor, rather than the person who went to Cancun for spring break last year or owns two dogs.