Both sides have valid points and arguments. Brutus did betray his friend by participating in the plot, but he did it for a greater good according to what he and the group believed was the greater good. On the other hand, Caesar was a tyrant and wanted to rule with an iron fist, which is what bothered people. So Brutus was indeed a traitor, having betrayed Caesar, but he was also a savior because he saved the people from Caesar.