For those who want the short review, it is quite simple: buy this guide. As to why, that will take a few more words. If you are not familiar with Future Press and their guides and you are a fan of any of the games they have made guides for in the last few years, do yourself a favor and buy one. The Portal 2 guide is their latest effort and it maintains the already stellar level of craftsmanship they have used with their previous guides. With an academic textbook level of information about the Portal 2 universe, this guide thoughtfully lays out each level with a very unique spoiler prevention system that allows the reader to decide carefully how much help they need. Since the joy of Portal 2 is primarily found in solving the puzzles, this retention of the core game's dynamic is key. However, after you have completed Portal 2 for the first time, the fun continues with trying to improve your times through each puzzle. This is where the guide will pay off the most. As with their Killzone guides, Future Press has given the player a multitude of data and insight into each level and has painstakingly broken it down so he or she can complete the game to its fullest. As I said earlier, this guide has an academic textbook feel to it because it encourages the reader to learn the game and to master it and gives you all the information you will need to be the proverbial top of your class. As an added bonus, the guide provides you with a complete written history of the Portal universe and how it ties to Valve's Half-Life. With beautiful illustrations and Future Press' ingenious code system that allows you to unlock extra content and videos on their website after you register your guide online, I can't imagine a more complete guide. All competitors should take note. If you are a collector, you love games, and/or you want to master Portal 2, I recommend this guide with my highest of recommendations.
NOTE: This review is based on the collector's edition. However, the bulk of what I have described in this review can be found in the equally well-crafted paperback edition which is more readily available (and cheaper) in North America. If you can acquire the collector's edition without breaking the bank, I don't think you will be disappointed.