First of all, the difference between the regular and collector's edition guide is the hardcover, additional concept art and a quick reference card. The Collector's Edition Guide has 416 pages instead of what's listed elsewhere (including on Future Press website).
The walkthrough is detailed but not necessary because the game is not only linear, it's guided linear (press Up on the D-pad to get directions). It is useful if you want to get trophies that don't come automatically with campaign progression.
The bulk of the book in on the multiplayer component, and that's where this book is brilliant. It covers in excruciating detail all the things FPS-crazy players will want to know - yeah, the numbers, ranking, experience, stats. Each player class comes with an in-depth analysis on their abilities, weapons and usefulness in different game modes. If you're new to Killzone, this is a quick introduction on the classes.
The 8 multiplayer maps are also well covered. There have both schematic and satellite views. On them are locations of the spawn area, ammo boxes, turrets and weapons. Each map is loaded with strategies specific to all the game modes, the favourable player classes and certain areas are zoomed in for future analysis.
At the back is the gallery which features beautiful concept art of the game. There are various interviews with the staff who talks more on the background of Killzone, the story and the production side.
On the last page is a code you can use register the guide on Future Press website to redeem 3 Unlock Points for unlocking abilities and weapons. Not much, but I like little extras like this.
This is a very comprehensive and useful guide. Multiplayer fans will benefit more.