When I was 12 years old my best friend gave me a copy of this book and told me that I might find it interesting. He could not have been more right, for I delved deep into the book and I finished it in a matter of 2 weeks (to me it was a record to finish a book so quickly at that age!) I found the book to be very informative and entertaining at the same time. The author, Mr. Dale Carnegie, will not introduce a principle or a notion without supporting it with at least one real life story where the principle introduced was proven effective. After that point I noticed a great, almost immediate, effect on my behavior as I was growing up. I noticed that I have become a very good negotiator with my parents and teachers, more popular at school, and I even began to understand people much better than I used to prior to reading the book. I grew up believing that this book was one of the greatest factors involved in shaping my character.
Recently though, I noticed some growing criticism of the book and its teaching, and I thought that this would be a good time for me to refresh what I learned from the book and assess its quality based on the experience I've gained since the first time I read the book. So I bought the unabridged audiotapes of the book and listened to it whenever I was in the car.
Mr. Carnegie said somewhere in the book that if one thing you learn from the book, which is the ability to understand the different views of other people in different situations, then that would be enough. And I agree wholeheartedly.
My judgment is that this book will indeed teach you how to understand the motives and the different forces playing in the different people you meet. Humans all across the globe share basic needs and characteristics that play a major role in forming their attitudes and decisions. Understanding those factors and satisfying them will be the most effective method of influence you'll ever need.
Mr. Carnegie begins the book with the foundations of developing this skill of understanding others. He extends three principles that if applied will help you identify what other people want and how you can satisfy them. After that he introduces six ways to make people like you. These methods hover around the same three principles mentioned in the beginning of the book. After that the author discusses in two parts methods and principles that help you influence people to your way of thinking.
All of this seems interesting but why are people criticizing this book, you wonder. The first issue with this book is the title. It says "How to win friends and influence people." I would have called it "How to make people like you and influence their behavior." The methods Dale introduces aren't for winning friends. You don't win friends by avoiding arguments and by projecting enthusiasm that is not honest. You'll only have them like you, but they are not won as friends, yet at least. Honesty is absent in Carnegie's teachings, and sometimes even unadvised! In one story he tells of a manager of a singer who would lie to the singer just to get him on stage!
Another observation I had on the book was the relevance of some of the stories to the principle being introduced. Some of those principles would not have worked in the stories he mentioned have the circumstances been even little different! Yet Dale would acclaim the introduced principle as the reason that the story reached the happy ending it did. But, to the benefit of the author, this happened only a few times overall and it doesn't degrade the whole quality of the book.
Nevertheless, the lack of emphasis on honesty is a serious issue. This has caused many reviewers to warn readers from reading this book. But here is where I disagree.
You'll need to read this book to learn the methods, not just to be able to understand other people, but also to be ready when others are applying them to influence you. I'll have to agree that some of these methods are extremely powerful especially if the receiver isn't ready for them. Reading this book will make you resilient to the weapons of many unwanted salesmen and negotiators.
My advice is to read but with caution. Learn the methods but always remember that honesty should always be present when these methods are being applied.

His advice is so obvious and so easy, so how come it's so difficult to do yourself and so rarely found in others? Is it cynicism or manipulation? No, it's human nature: Do Unto Others ...
THE FUNDAMENTALS
? "Speak ill of no man and speak all the good you know of everyone."
People react very badly to criticism; don't do it, not to their face nor behind their back ... especially not behind their back.
? Say "Thank You".
Express appreciation. People yearn, yearn to be appreciated.
? Talk about what people want and help them get it.
"Arouse in others an eager want."
Corollary: let others take credit for your ideas; they'll like your ideas a lot more if they believe them to be their own.
WAYS TO MAKE PEOPLE LIKE YOU
? Be happy to see people.
Greet everyone you meet and show an interest in them. Remember the things that are important to them.
? Smile!
? Remembers peoples' names!!
Remember it, use it when talking to them. A person's name sounds beautiful to them.
? Draw people out.
Encourage them to talk about themselves and their interests.
? Actively research the other person's interests.
? Every person you meet feels themselves superior to you in some way.
Strain to find out what that is and recognize their importance. Talk to people about themselves and they will listen to you for hours.
WIN PEOPLE TO YOUR WAY OF THINKING
? Don't argue!
Give in! Agree that the other person is right; often they are and if they aren't, you'll never convince them of it by arguing.
? Don't ever tell a person they're wrong.
They may be but telling them so is always counterproductive. It is difficult for a person to admit to themselves that they are wrong; harder still to admit it to others.
? If you know you're wrong, admit it.
Openly and freely admit whenever you're wrong. And always leave open the possibility that you're wrong even of you think you aren't.
? Friendliness begets friendliness.
Always begin that way. Don't accuse.
? Never neglect a kindness.
Look for ways to do or say something nice.
? Start out by emphasizing areas of agreement.
When a person has said "no" it's hard to get them to change even if they know they're wrong.
? Let the other person do most of the talking.
Listen patiently and don't interrupt. Let your friends be better than you.
? Let people come to your conclusions.
First, tell me what you expect of me; then tell me what I can expect of you. People will generally live up to the commitments they make to you as long as they came up with them on their own.
? Think always in terms of the other person's point of view.
Where they stand depends on where they sit; figure out where they're sitting.
? ? of the people you will ever meet are dying for sympathy.
Give it to them and they will love you.
? A soft answer turneth away wrath: but grievous words stir up anger.
? Dramatize your ideas.
"Don't use logic; tell stories." Make your ideas visible, concrete. Bear in mind that people don't know until you show them what you mean.
? Stimulate in others their innate desire to excel (perhaps through a friendly challenge or through competition).
BE A LEADER
? Don't go sailing into difficult interpersonal situations with guns blazing. You'll always get a negative reaction.
? Change "but" into "and".
Be indirect in your criticism. Praise before you condemn.
? Ask questions rather than giving orders.
? Be very careful to help others preserve their dignity.
? People crave recognition: praise the smallest improvement and praise every improvement.
? Treat people as though they had the virtues you wished they possessed.
Give them a reputation to live up to and they will work like crazy to live up to it.
? Praise the good; minimize the bad: encourage.
Make achievement seem possible. Take and encourage little baby steps. Seek out even the most insignificant of successes.
? Napoleon: I could conquer the world if only I had enough ribbon.