The Art of Halo is a great, interesting resource for Halo fans that sadly doesn't overstretch itself and become the more widely recommendable book that it should be.
The Art of Halo contains a higher text to image ratio than the other artbooks I own. It seems to me that the images suffer as a result, with some sidelined and reduced to miniature size. Forgivable perhaps, so long as the text is worth the loss: Unfortunately, the text contains far too much gushing praise for Halo and Bungie, and far too little actual information about the design process, such as you might expect from a book subtitled 'Creating A Virtual World'. There is also a tendency for repetition that goes unchecked, either between team members, or image captions and the main text. The most disappointing problem with the text is its tendency towards basic information: a character or enemy's role in the games, fictional background information on locations and weapons. The kind of thing already in the game's manual and strategy guide and completely irrelevant here.
By far the poorest section is that devoted to weapons. The text here is illuminated by scarce gems of background information, and the image content is even worse, nearly exclusively composed of in-game screenshots and final model renders with concept art available for the minority, it has very little to offer that anyone familiar with the games don't already know, and non-players are unlikely to be interested in such details anyway. Thankfully, other sections are a lot stronger: the Environments chapter is particularly interesting, and contains a more acceptable amount of unfamiliar concept material. Still, my overall feeling is that the book could have contained far more conceptual designs and anecdotes, and far fewer images of in-game and finished material (there is also an inappropriately regular use of outdated E3 2003 demo content). Sometimes the layout of a page isn't perfect either, with large highly detailed images relegated to thumb-sized squiggles in favour of useless text or huge reproductions of simpler works (on page 57, for instance, we lose a beautiful looking Gravemind study to a very pixelated and far less interesting early study that for some reason takes up a quarter of a page). There is also a bias towards the (then unfinished) second Halo game, apparently symptomatic of Halo's troubled and rushed development.
The book is printed with high-quality materials but sadly lacks a hardback edition for true collect-ability. It is also not overly long at 161 pages. At its height it is a marvelous visual delight and an interesting read, but it fails to sustain this level of content and is unlikely to interest non-fans of the game. But then, there are so many Halo lovers out there that the book certainly has a wide market anyway.