There is no "one" reason I bought the guide book. There are many reasons, including info on where and whom to get trained by, where and how to buy houses (ie, what quests to do to get them), a list of all enemies in the game with all details such as how much health reserves they have, maps of every cave, dungeon, city, castle, etc. It's already helped me out in my quest to get my favorite steed Shawdowmage. I've wanted that horse since I acquired it in Oblivion for it's faster speed and higher health reserves. He helps out a lot in fighting larger enemies. I wasn't sure if he was even going to be in Skyrim or how to get him. Now I know he becomes available after doing a certain quest for the Dark Brotherhood.
Can most of this info be had off the internet for free? Sure, if that is you know what you're looking for. To me, the $16 I paid for the guide book is totally worth it just to have the info always at hand. I hate quitting the game to go look something up on the internet. It also recently helped me to find out how to cure a disease I got somewhere. Before this game, I never really understood why anyone would buy a game guide, but then I've never played a game as involved as this one either.
Btw, speaking of the Dark Brotherhood. Is it bad that these are the quests I enjoy the most in the game?
