Books about current art, like the art that they describe, often don't age well. This is particularly true for books about digital art. There is often a confusion between technology as means and technology as subject. There is often a confusion between digital art with something new to say, and what is simply a breathless and complicated demonstration of technology that will be routine within a couple of years, or something that would be far more elegant without the unwieldy overhead of intrusive technology. There are often tiny, crabbed pictures of huge one-off installations surrounded by oceans of text, kind of like watching the Technorama version of Lawrence of Arabia on your iPhone.
A Touch of Code gets it right. It's current as of 2011, and the format gives the works enough space to actually understand what's going on. More importantly, the artistic signal to self-congratulatory noise signal is very high compared to most books in this genre. Most of this stuff is art that is genuinely interesting, much of it is designed to be replicable or a long-term installation, and a significant chunk of it will still be interesting twenty years from now. For the first time, I have a sense of how technology might become a genuine tool for art with considerable impact and lasting value. In this text, they tend to be the works that use technology as tool rather than technology as subject. But like most good art, the conceptual payload includes a subtle encapsulation of the time, place, and zeitgeist that it was created in.
If you get one book on digital art, right now this is the one to get.