The better the tool the less you learn from it. There was an experiment, I don't have a link, read about it someplace, about a task two groups of people had to solve on a computer. In one case the tool was merely checking the final answer; in another it was also offering helpful visual clues during the solving. Both groups solved the problem, but a follow-up check revealed that the first one has built a somewhat better understanding of the task, a better mental model of it.

I think this is same with today's maps: it's very easy to find a road with a navigator, but it doesn't leave any lasting impression. Fine if it's a one-time task, but not that good if you want to become an expert on local roads.

With a PDF about data structures you do have the executable environment: the compiler or the interpreter the PDF uses to give examples. The compiler has no manual on data structures, but you have the PDF instead. This is the real thing, by the way, that compiler. An medium that combines both instructions and some interactive thingie that shows the data structure will be much farther from the actual compiler than that poor PDF.