There are arguments to be made for both sides of this issue.
Some people would say that President Ford made a mistake. Such people generally argue that Ford should have let Nixon be charged with a crime if prosecutors felt it was appropriate. They say that it would have shown that no one is above the law. This would have been a good thing for all Americans to know.
However, there are many who say that Ford’s actions were the right thing to do. They say that putting Nixon on trial would have been damaging and pointless. All it would have done, they say, is to prolong the national focus on Watergate. This would have made people feel worse about the country.
My own view is that nothing was to be gained from trying Nixon in a court of law. His career was already ruined and he was completely disgraced. His legacy would never recover. In short, he had been punished enough.