Maeda is a certifiable genius, but his books have gone downhill since his first, "Design by Numbers." That book is an exceptional introduction to computational design, original, and elegant. His next, "Maeda at Media" took many hundreds of pages to sum up Maeda's years a the MIT Media Lab. It was something of an egotistical embarrassment. Maeda, then just in his mid-thirties, included pretty much every experiement and project he'd done to date. Even geniuses need editors.
Now, in "Creative Code" we get a book not really different from the "New Masters of Flash" series that's now in (I think) its third edition. CC is a collection of case studies of work by some very smart people, and some essays about digital media, working methods, and so on. Much of it is great work and pretty. It's rendered pretty lifeless in a printed book, of course, so you'll want to track down this work online to actually check it out.
How valuable will this be to you? Do you need another heavy, sexy design book? If you're really interested in this kind of work, you'll certainly already know about all of these designers, and probably about most of the peices included here. You've probably also read the designers' own blogs or web sites, so you'll know about their methods and interests in much more detail than you get here. (The description's statement that "little of this research has been seen outside the laboratory" is not true.) In that case, you get a book of pretty pictures that probably will sit on your shelf more than on your lap. If you're looking for code samples or detailed technical explanations, you'll be better off looking elsewhere.
It's kind of a shame in the end. He's so talented, I want to see Maeda doing less surveying of the state of interaction design and more genuinely innovative and interesting things. In fact, I'll tell you what's needed: to finish the project he started in DBN, which is to really explain the concept of "coding elegance" (and the creativity behind it). There's a lot in all three books about the aesthetic appeal of well-written computer code, but there's not much about what specifically makes one algorithm more beautiful than another. This algorithmic elegance is really central to Maeda's work; he says that digital designers should appreciate both the coding and the visual/interactive design natures of the medium. The people represented in this book are the ones who'll be able to do that, but it hasn't happened yet.