I think Spring Data is an amazing piece of technology, and every developer using Spring should learn it. However, I would recommend that beginner's learn it. I think Spring Data has it's place in a beginners book, but it should be after you have covered core concepts.
The thing is Spring Data introduces a paradigm shift that a lot of people don't realize. Until now, interfaces were treated as contracts. Basically, your interface describes what your class can do. What Spring Data does is make interface a specification for code generation tools. That's a completely new use of interfaces that you don't see anywhere in the
Java world. It's a paradigm shift that I call Interface as Specification.
THe problem with learning Spring Data as a beginner is wrapping your mind around the Interface as Specification concept. It;s a little hard to digest. Most people start wondering how exactly the DAO layer works.. "Where is my DAO class?!" If you want it in a beginner book,
you should really have it at the end.