In the movie Braveheart he was portrayed as ruthless and that was probably not the case in real life. In reality, Scotland asked him to come help out under the condition that Scotland was a part of his kingdom for a time and was returned. He did break his word in this case, but he never took Scotland by force.
While a lot of things that Edward Longshanks did seem cruel, backward and even evil to the modern eye, you have to take into account that he lived in the 1200-1300's AD and the world was a different place at that time. Cruelty was common, there was no intercultural understanding, war was a daily event and cooperation between people and nations was not yet typical. Given this, it is unfair to call Edward Longshanks evil because it involves applying standards that would have been unheard of in his lifetime to choices he made.