As a current Duke 3rd year, here's my two cents.
I chose Duke quite simply because of its innovative, unique curriculum...I didn't really care where it was, how it was ranked, etc....I just wanted to be in a place where I wasn't going to be forced to spend two grueling years in the classroom memorizing minutia that I wouldn't even remember a year later anyway, and which to be honest really isn't important in the practice of medicine. Getting onto the wards a year sooner is a HUGE advantage, because the sooner you're immersed into medicine as it's really practiced the better you'll be when it really counts, when you have REAL responsibility and life or death situations as a resident. For me, this opportunity makes Duke the best of all possible programs, but of course it isn't for everyone. However, it's important to recognize that contrary to popular belief, Duke does NOT squeeze two years of basic science into one. I can't stress this enough. There are simply a lot of things we don't do in the classroom. Given the rapid development of science and medicine, Duke recognizes that you simply can't learn it all, and so we don't spend time doing a lot of things other schools do because we don't think they're as important as clinical experience. When you can't learn it all you must make choices, and Duke chooses differently than most schools, but I think it's very much for the better. This is especially true for me as I'm not a great didactic learner. But once I got onto the wards and was able to put things into the context of a real patient, and see how disease really presents itself, it made an enormous difference in my education.
I also think this is an advantage from a USMLE point of view, as Step 1 is very much a clinically-oriented exam despite being a test of "basic science." Of course, during first year we learned all the basic science we needed in order to do well on Step 1, but we also get to amass tons of clinical knowledge that most other students don't because they aren't even allowed on the wards until they pass Step 1. I think this is one reason why Duke students do so well on the boards...most of my class hasn't taken Step 1 yet, but of the few who have, I've already heard of 3 students who scored over 250!!! The national average is 217, with a standard deviation of about 23, and as a previous poster noted, the average Step 1 score is in the 230's at Duke. I imagine this puts Duke somewhere at the top nationally.
What I see as the other enormous plus of the Duke curriculum is the third year. While it is a "research year," please don't get the impression that you must spend your 3rd year pipetting your brains out. I really abhor wet lab research, but I haven't had to set foot into a lab here. To give you an idea what some of my classmates are doing, I'll try to break it down quickly. There are around 10-12 MD/PhD students, then about 10 students getting an MPH at UNC Chapel Hill, two more getting an MPP (Masters in Public Policy), a couple doing humanities work in medical history and ethics, one getting a masters in philosophy, a number doing clinical research, at least 4 or 5 at the NIH in their "Cloisters Program," etc. etc. Clearly, there are a LOT of options! For me, the 3rd year is enormously valuable, because I'm able to get a degree that would take me at least an extra year to do at any other school, if even available. This realy helps open up career options, and I imagine makes you more attractive as a residency program applicant. In addition, for those interested in very competitive fields like ortho, optho, derm, radiology, and the like, the 3rd year is an opportunity to do research in that particular field and also do clinical work in that specialty, thereby allowing you to not only test out whether or not this is really what you'd like to do with your life, but also to make connections with people in the field and to even get a publication or two under your belt to really show how dedicated you are to this specialty. I think this is a HUGE advantage. Students at most other schools often have a very difficult time squeezing research into their medical careers, and often feel pressured to do so despite the difficulty, particularly if they're aiming for a very competitive specialty. This quite simply is not a problem at Duke!
Anyway, I hope that helps. Feel free to PM me if you have any further questions. I love Duke!!!