Gabriel Knight: Sins of the Fathers Hint Book is the official hint book for the original Gabriel Knight 1.
It is generally basic Sierra hint book similar to other hintbooks published by Sierra in the early 1990s. But it does contain some extras such as character biographies, some additional notes with information about Voodoo and New Orleans, a 'did you figure out' section that explains further details of the game's plot (similar to the King's Quest 6 Hint Book).
The book is divided into days (with game's poem quote for each day). Each of these sections contain general hints for each location on that given day.
In the back of the book is a 'did you try' section that points out some of the incidental things you can discover in the game. Like using items in unintended ways (but will give out interesting reactions), or differences in puzzle solutions/conversations at different specific points in the game.
There is a straight walkthrough section that explains all the main actions throughout the game. It takes the approach that every action is taken at earliest possible point in the game. For example all things at Granny's house are more or less finished on Day 1 (though many of those same things could be done on later days).
The last sections include the game credits, and maps of the Snake Mound and Voodoo Hounfour.