While this guide is very nice to look at, I would use it with caution if you're aiming to complete the game 100%.
On the surface, it seems like a very in-depth guide, but there are several issues I have with it.
For one thing, it is very redundant. Things are explained in text, and then again in separate bubbles on the same page. Perhaps it's to catch the eye, I'm not sure, but I feel like a lot of space was wasted in this manner. This happens on every page.
Second, the pictures are rarely helpful, and very small so it's difficult to make out too much detail. I feel like they're just there to make the page look colorful. Also, the directions are often extremely vague (i.e. Go to wall and do this- but there are multiple walls in the gigantic rooms you find yourself in). The maps are entirely unhelpful, and the exact ones can be found in your in-game menu.
It is also relatively inconsistent. Often, quests are described in detail if they are available in the current area, but I have found a couple of instances where the quests are only mentioned as a brief blip in a side bar. In these instances, the quests happened to be only available under certain circumstances or were only available in a limited fashion, so I was confused as to why no attention was drawn to these as well.
One thing in particular really bugged me that also had to do with consistency- most of the time "Junction Points" were outlined in their own special box on the page, warning you that the decisions you make at that point in time will affect the ending of the game. Well, there was at least one "Junction Point" I was not warned about at all, and completely messed it up. I only found out about it way too late, after I had done it, when I found it in the back of the book that this minor action I did several hours ago was considered a Junction Point. No warning whatsoever, aside from a sentence later on that says "oh yeah, if you happened to do this, you can't do this quest." After it's way too late.
There are other minor errors and things strewn throughout, but nothing I think as notable.
The guide often repeats that you'll need three playthroughs to accomplish everything. Technically, you only need two, but if you're using this guide it will probably will be three.