There are many different kind of technology books. Some books introduce the reader to a specific technology or to a concept. Some books are references, some teach the basics of programming (or some other elementary concept). Some books do more things at once.
Some books last. When a book does not teach a specific technology (that is transient, by its own nature, and changes) but a broad concept, they are more likely to last (perhaps with minor modifications). The books I love most are part of the second category.
A particular category of technology books are the ones teaching new programming languages. If the programming language is a good one, the books tend to lean towards the second category, the one of books teaching broader concepts, even though perhaps they need more frequent updates, as languages evolve.
Perlis said that: "A language that doesn't affect the way you think about programming, is not worth knowing." And I could not agree more. Some languages improve your programming in every other language. Lisp is one of such languages. Nice dynamic OO languages don't do that automatically, but in the hands of a careful programmer, they have the same effect.
So, if the language is good and the book teaches you how to actually think in the language, how to use its proper abstractions, then it is teaching you something noteworthy. Unfortunately, sometimes there is so much language to teach, that there is no more space for anything else (C++?). Moreover, some languages just teach programmers to thing the wrong way (C++, Basic).
But this does not really concern us, as we are going to talk about Clojure. Clojure is a wonderful language (even though I actually favour Common Lisp).
Right at the moment, there are two book on Clojure. I already reviewed Programming Clojure in a previous post. The "other" book about clojure is "Practical Clojure".
From a typographical point of view, Practical Clojure sucks. I just hate the way APress books are typeset. I hate the fonts. I hate the spacings. It looks to me as it was paged with word. On the other hand, I rather like the Practical Bookshelf paging, indeed. Still, I find I prefer more the typesetting of some more traditional editors (e.g. On Lisp, most stuff from MIT Press, or even some newer stuff such as NoStarch Press Land of Lisp). But of course it is content that matters.
Practical Clojure uses a newer version of clojure and that is an advantage, of course. A part from this, it is another introductory book on clojure. There is a wide intersection area on the subjects, but the two books have some differences.
Practical Clojure introduces Java interoperability at the end of the book and that means that most examples are "pure clojure" and some central chapters can be used as a reference. Consequently I sometimes read through Practical Clojure even now. I also find some explanations more thorough.
On the minus side, there are fewer long length examples. Consequently, it is harder to figure out Clojure pragmatics. I believe that we really need a different breed of books. Practical and Programming Clojure basically show us the basic Clojure constructs and how to use them. They are introductory books on Clojure (and we need these books as well).
I believe that we need books that build on those two to go deeper. Some books on Lisp are old, but still teach the abstract principles of Lisp programming. Consider for example Graham's books, or PAIP. We need something like that for Clojure. In fact, I'm looking forward to read Joy of Clojure.