I love the game, but having played through with this guide, I'd have to say that the walkthrough doesn't do it justice. There is nothing in the guide that is a "must-buy" or significantly enhances the story. The background character profiles are the ones from the game, so they may help people unfamiliar with the DC universe to solve some of the Riddles.
The maps in particular are a let down; it's difficult to figure out which icon relates to which solution and the Riddler Secrets Maps in the game perform almost the exact same job. I think the only time I used the book maps was to find a couple of Joker Teeth right at the end.
The tips for the Challenges are useful, if not fantastic.
In all, the various online guides and the plethora of videos they contain make a much better medium for the walkthrough than a printed one, although it is nice to have a printed reference rather than a laptop next to you.