I interviewed at Mayo-R and have interacted with a few of their physicians and researchers outside of my interview as well. From what I have understood, the entire institution is geared towards "the most effective delivery of care to the patient". This is almost all pervasive and really seems to influence everything in that institution. E.g. a lot of research is focused on constantly improving outcomes - to the point that it is often the dominant kind of research happening there. Not that there is any issue (its a good thing) but thats what I mean. And they will keep polishing their outcomes till they are perfect.
In order to deliver the most effective care, they obviously will not throw residents into the fire. e.g. in a few institutions like BU, Baylor and from what I hear UTSW, you are often given loads of autonomy and responsibility. But in Mayo, it appeared to be more graded. People complain there arent enough procedures, but from what I made out on my interview day, you need to achieve a certain level of competence, through their simulation center (which is phenomenal), before you can have a go at the patients freely.
So from what I made out, it is a "system of functioning" - and you learn how to function in such a system. How to develop the appropriate competence, and look into many issues in order to manage patients. This can often frustrate those who "learn by doing" and want to have a go at things from the first day itself.
Also, because of the kind of research done, they do not do as much bench research as some of the other academic institutions. So if that is something that you are seriously looking at, you may have to bend your bench research interests in order to match those of the faculty at Mayo, That is something you may or may not want to do. And obviously the options are limited.
So thats what I meant by delivery of care. If you want to learn how to really go the evidence-based way to continually (and almost microscopically) improve outcomes, and focus on minimizing errors, etc. I felt that Mayo just does a phenomenal job teaching you that. I am sure a few other programs do too, but I just felt Mayo functioned at another level (I did not visit some of the real big name programs, so I cant comment on those).