How does it achieve this ranking and what makes it so good? Is it worth going to Duke for the food alone?
Duke dining is exceptional and simple to use. Each semester you get “food points” (equivalent to money) that are loaded onto your DukeCard. When you want to eat you swipe your card and spend some food points.
Duke is #1 because of the variety of dining options (every type of cuisine you could want including Italian, Southern, Indian, Japanese, Stir Fry, Salads, Burgers, 24/7 options etc.), the prevalence of restaurants and cafes around campus and the high quality.
Since Duke is a campus university (we are not inside a big city like New York or Boston), the school have made a huge effort to offer a range of options on campus. That said, you can also order food from off-campus restaurants and have it delivered to you using food points. Durham (the city Duke is in) has been ranked #1 in the nation for small-town food - there are a ton of great places to eat in Durham.
Dining, trivial as you might think, is a good thing to consider when deciding where to apply and attend (that’s why Duke just spend millions improving our dining).
Here’s a picture of one of a new dining hall, West Union:
http://www.architecturalrecord.com/ext/resources/Issues/2016/Nov/building-type-studies/1611-Colleges-Universities-Grimshaw-Durham-North-Carolina-West-Campus-Union-01.jpg?1478198113