It depends on your approach IMO.
You certainly have to be specific with your choice, since many books are about stylistic play and you must be comfortable adopting someone else's comfort zone, so to speak.
But some things are universal, like outs and odds
. And many better books are also more about getting a player to think about why he wants to do something, and this is great. You should use forums such as this one to keep up with the present dynamics, and think of books as a cafeteria. There is a lot offered, and its up to you to sort through what is good and what not.
In any case, if a book gets you thinking about specifics, and makes you question whether or not you made a correct play, and that prompts you to posting hands and discussing what your thought process was etc., then the book is more than worth the price and time spent reading.