Yes, chess books definitely help you! They provide insights that you have never seen before. Indeed, if you do not have a coach to help you with your analysis or openings, a chess book is the way to go! Puzzle books, for e.g. can actually help you train speed thinking and your tactical vision.
Nevertheless, I believe that one must be discriminating when choosing a Chess Book. As the famous author John Nunn aptly pointed out, some books are actually not well grounded and are full of blunders, merely a means to get some quick money! Therefore, when choosing a chess book, I suggest going for books by reputable authors and also flipping through the book slowly to see if it really provides the material relevant to your area of intended study.
Well i recently just finished studying two chess books, The Complete Book of Chess Strategy and The Complete Chess Player. I have to say that reading chess books has improved my game A LOT!! I notice that even if i tend to forget something i read in the book, somehow my mind can maintain it and express itself whenever i see the chessboard. big advice: read chess books to get better. they actually do help you. I've been playing as I've been reading and i thought i didn't know anything different, or at least see a difference in my performance. then i went away on vacation and brought them along, i came back with a fresh mind and bam, i know good tactics and chess strategies. woohoo!