This book is about making people like you. However, most of the techniques tought are much too simple and ineffective.
When I was reading the book, I was surprised to recognize many little tricks people were using in order to have their way with me. These tricks were so obvious that I always wanted to ask the people: "Just how stupid you think I am? Do you really think I'm not seeing what you're really up to?" Most of the techniques Mr. Carnegie suggested were very easy to recognize and there was no chance anybody could make me like him by using'em.
At that time, I was everything but advanced in psychology. What I'm saying is that when you use Mr. Carnegie's tricks, there's a great chance that people you're dealing with will recognize them and react negatively. The book is easy to read and can certainly give you some good basics on human psychology, but if you want to be really successful in your communication, you'll need much more than Mr. Carnegie's ancient wisdom. (Besides - I can't let it be unmentioned - on a few occasions, the good old Dale Carnegie is simply wrong.)
There is one more thing you should know. When Mr. Carnegie talks about "friends", he means "customers". You might make customers with his techniques, but you probably won't make any friends. In fact, you should be careful with using some of Mr. Carnegies tricks on your friends if you don't want to lose them.
I'm not saying the book is bad. I'm not saying it's good either. It's mediocre, no more, no less - that's what the 3 stars're for.