For teenagers, the cons of having a curfew can mean it limits the time that they get to spend with their friends. It can also restrict their ability to take care of themselves, of which they feel they are completely capable. The positives of having a curfew for teenagers means that they will be in a safe place at night while at home. It can also help ensure that they get the amount of rest that teenagers need while growing and teach them how to abide by rules.
Curfews, especially those that are implemented on a citywide level, have been debated by different parties for decades. Many argue that having a curfew prevents the victimization of youth and also helps to remove youth from the streets, thereby reducing the chance of them getting into trouble. Those people who are against curfews argue that there isn't any solid evidence of this helping to reduce crime.
In addition, other groups, like the American Civil Liberties Union, note that it's a violation of the constitutional rights of both parents and their children. It is believed that these laws limit their right to free speech and also violates the right of privacy that parents have for raising their children.