Famous airplane test pilot Bob Hoover was flying back from an air show in San Diego when all of sudden both of his engines cut out. Through some impressive flying he was able to land the plane, saving those on board. Unfortunately, the aircraft was badly damaged.
The reason for the harrowing engine failure was that the World War Two propeller plane had been accidentally filled with jet fuel.
Back at the airport, Hoover saw the mechanic who had made the mistake. The young man was in tears, knowing how furious Hoover must be over the loss of his expensive airplane and the danger posed to the three people on board.
So did Hoover yell at him? Scold him? Criticize him?
Not at all. In fact, Hoover said that to demonstrate his faith in the mechanic having learned his lesson, he'd like the same mechanic to service his plane the next day.
The reason for Hoover's benevolence was perhaps that he knew something that psychologist B.F. Skinner had discovered a long time ago: animals rewarded for good behavior will learn more effectively than those punished for bad behavior.
The same is true of people: criticizing them won't encourage them to change their behavior because they're not primarily driven by reason but by emotion. Thus the person you criticize won't truly listen to what you're saying. They'll just feel like they're under attack, and their natural reaction will be to dig in and fight back.
So while voicing criticism might help you blow off steam, in the long-term, it will just make others like you less.
Many successful people actually made it a habit to never openly criticize others. Benjamin Franklin, for instance, claimed that the secret of his success was to "speak ill of no man."
Abraham Lincoln learned this lesson as well. He used to publicly criticize his opponents until one day his criticism so offended someone that he was challenged to a saber duel! The duel was only called off at the last instant, and from then on, he stopped openly criticizing others. Even during the Civil War he famously told those who spoke harshly of the Southerners, "Don't criticize them; they are just what we would be under similar circumstances."
Criticizing someone is easy, but it takes character to be understanding and to forgive others for their mistakes and shortcomings.
So if you want others to like you, think about why they did what they did, accept their shortcomings and make it a rule to never criticize them openly.