I've read it and I think some of the parts brought a lot more depth to the story and characters. It was interesting to see what Low was thinking during all the different points of the adventure.
The parts I didn't like were those that tried to include some of the puzzles in the book. All of them just weren't logical, but since it's difficult to turn an adventure game into a novel, I'm not complaining. Too much.
If you're interested, there's a short conversation on how the German language is used in the book right over here.