It depends. if you are getting a lot of information out of it and you enjoy reading it, keep buying it. If everything you read in there seems like you already know it, and you don't want to spend money on it, don't. I personally don't read it, because I can get all the information I need on this site and others, and I don't like spending money on things I don't need or things that I can save on.
-You can search all day for something and never find it, only to see it in the most obvious of places after you've stopped looking.-