I'm a big fan of '28 Days Later' and I bought this a couple of hours after seeing '28 Weeks Later' as it sounded like some interesting background material. Firstly, I should point out that it's a graphic novel, so if you're not a fan of the genre and/or the films then I would look elsewhere.
The book is divided into four short stories, charting the progress of the outbreak seen in the first film. Each one is entertaining enough in its own right, but none of them have enough time to go into much character development or anything of that nature. I also felt that they didn't add much to the story that we don't already know from the films, so don't expect any of the questions raised in the films to be answered. Also note that none of the characters featured in either of the films are in this book, which I don't think is a problem, but that might be a disappointment to some readers.
The blurb on the back of the book suggests that some sort of shock revelation will be revealed, but I didn't find any surprises at all. I also found that the tension and horror experienced in the films is almost completely absent as a graphic novel simply can't be very scarey, and doesn't capture the aggression of the Infected.
In short, the style of the artwork and the stories are good and in the spirit of the films, but the book isn't very long and doesn't contain anything shocking. That said, if you're a fan you'll probably like it. "