There are certainly people who hate Islam. Generally, they are motivated by one or both of the following things:
First, some people hate Islam for reasons of faith. They believe that Islam is an incorrect religion. Some Christians, for example, believe that Islam is heretical because it does not believe Jesus was actually God.
However, just thinking a religion is wrong and hating it are different things. I would argue that many who hate Islam do so because they confuse the faith with the actions of some people who profess that faith. In other words, they hate Islam because some Muslims, claiming to act in the name of God, have done evil things. This, I would argue, is the case with most Americans who hate Islam. They hate it because they believe that Islam as a religion leads to actions like those of Al Qaeda.
I think often peoples' hatred of Islam is fueled by misconceptions. Often in the media, Muslims are often and consistiently portrayed to be evil and bad. That has become a common streotype. The true beliefs of Islam are completely opposite of violence. They believe in peace and non-violence. I find it is most often better to foster your own ideas then give in to media hype and stereotypes.