He funded terrorism over the years, and has always gone against peace. He does not believe in the people of Libya having a voice, because he goes against the demonstrators with acts of violence. He has also stated several times that there would be blood shed if protests continue against him.
It's difficult to say with certainty that Libya will be a better country if Qaddafi is overthrown, because I know so little about the opposition forces and what type of ruler or system would fill the power vacuum if he's gone. As it stands, though, he is a dictator who seems to be governing over unwilling subjects. So, I believe that a new system is, more likely than not, a step in the right direction.
It's not significant enough to say it will be a better place. What needs to happen is, radical Islam needs to be overthrown so we can stop hearing about how America is responsible for everything happening in other countries. Once that happens and the corruption is gone maybe them and the middle east can finally and hopefully get on their feet.
Libya as a nation has many serious problems, and I do not believe that overthrowing Qaddafi will solve them. Although Qaddafi has done many things to harm the Libyan people, him being gone will not change the region's unstable political climate or improve the country's devastated economy. His removal also creates a power vacuum that may cause warfare among Libyan tribes.
There are many situations in the world where getting rid of one dictator merely causes another to rise and take the old one's place. The overthrow of the Shah of Iran, ousting the Soviet Union from Afghanistan, Saddam Hussein in Iraq - all of these were actions that the US took in the name of freedom and liberty, and which saw villains who were just as bad, if not worse, than those that we helped to overthrow. Given that there appear to be many in the Libyan rebellion who are members of the Muslim Brotherhood, we may come to see that Libya will just be another despotic theocracy, just as much of a threat to the world, if not more so, than Qaddafi is.