The author admonishes you, in his foreword, that you must have some kind of poor economic judgement, to be buying this book when the comic is free online.
But that does more to illustrate the kind of wit he has, than represent the truth, because the book is NOT a print-out of the pics you can get online, but is apparently based on the original, pen/pencil drawings (at least in part), giving you a (faint) insight into the process of their creation, plus giving a feeling of something authentic, like buying a cell from some favorite animation.
If you have NOT read the comic online, the domain name is XKCD (as you can infer from the name), go read it. If you'd have liked the book anyway, you'll be back to buy it out of sheer joy for the sarcky satire you've experienced.
Who will like XKCD?
* Anyone who likes Big Bang Theory. This is the one source of "nerd/geek" humor superior to that one.
* All Wikipedians, except the anal-retentive ones who didn't even want us to redirect the word malamanteau to the XKCD article.
* Those who are disgusted with "SyFy" for being ashamed of science fiction. (google "syfy, we disown you")
* The kind of people who hear about MIT pranks and think "I could have done better".
* Problem-solvers who, upon realizing that the a-hole ops of #Linux answer every question with "RTFM", spoof another IP while running a hacked ID validator and give wrong answers to their own questions, baiting the experts into jumping in with corrections. And then go help run #linpeople to answer the questions right.
* People who, having studied linguistics, math/physics, logic, engineering, or some other intellectual discipline, determine that the greatest benefit is all the extra puns it allows them to notice.
* Sarcastic romantics
* Pseudointellectuals...OK, they won't, but they'll feel obligated to pretend.
* I will. Did. Do. And that's what counts.