I picked this up after I'd already beaten the game, and I'm glad I didn't have the distraction of all the goodies buried in the guide to drag out my already very long campaign.
Extremely helpful if you're chasing all of the optional objectives in the chapters. The walk-throughs are immensely detailed, with step-by-step instructions, including pictures, and tips for finishing each Chapter in each play type. Most chapter write-ups are in the Ghost style, avoiding all killing and knock-outs. That doesn't mean that there aren't sidebars to explain how to get through the chapters if you're trying for Opportunist or Predator endings.
There are also detailed City walk-throughs, split into 5 sections that match up with where the city undergoes major changes within the game. For example, City I is the city after Chapter I. City II is the city after Chapter 3 (I think... going from memory here!), etc. As you discover areas of the city via the chapter stories, or the city changes because of actions of the chapters, the guide has a City walk-through to guide you.
The treasure walk-through is anal-retentively detailed! (Loot, Collectibles, Documents) Everything is numbered, starting at 1 and numbered in an order that makes sense by how you would encounter than in the game. It takes a little getting used to, but once you get it, it is extremely powerful in getting you through to Completionist!
I like this guide, so I gave it a 5, however there are some mistakes.
Chapter 4 - A Friend in Need. There is a gear that you need to obtain when you're down in the pipeline. The guide tells you to jump down on the 1st unstable platform, and then jump across to the 2nd one, then run across it before it has a chance to fall to the pipe below. That isn't correct! You have to jump down to the 1st unstable platform, and then SNEAK completely across the 2nd platform. It took me about 30 tries to get that stupid little gear!! Save yourself some sanity.
If you're going for Predator or Opportunist and dealing with Freaks - don't bother with anything other than Blast Arrows if you plan on killing a Freak directly. One Blast Arrow will down a Freak. However, you will use 2 or more Fire Arrows trying to kill Freaks by shooting them, even using headshots... Even with headshots using the Marksman skill (which uses too much Focus, IMHO). Save the Fire Arrows for those nifty "oil slick" shots that will nab you Opportunist points. And don't even bother with non-fire-based arrows. (Flash Bombs are fun.)
The Guide has nothing in it about those eerie candles that you light using Fire Arrows all over Stonemarket. (The glowy talking ones...) From what I've read, once you find all of them, you get a Focus Point. I'm guessing that's why I have 1 Focus Point left to be upgraded and the Queen of Beggars won't let me buy anymore upgrades. Somewhere, I'm missing a candle!
A tip, this is in the guide, however not obvious right away as its buried in the walk-throughs... don't waste your expensive arrows on knocking crap down! Use your Blunt Arrows to do that kind of thing. (Lights, ladders, etc.)
One thing I wish the Guide had and it doesn't... How to make enough cash to afford the expensive equipment. I'm redoing all of the chapters and side missions, but I've only made about 3 grand. Admittedly, I like to shoot stuff, but with the amount of treasure in some of those chapters, you'd think I'd be making progress...