There are potentially many good things that could happen because of cloning that we discussed in the pro page. But many people are adamantly against cloning.
If the future makes cloning a reality, there will be many religious people that will oppose any scientific progress. Many believe that God created man, and that to interfere would be an abomination.
Also there is great concern about mutations. If genes and DNA are not used carefully, it may be possible to create an animal with super strength or a human with abnormal capabilities.
Finally, we believe that there is a concern that certain countries may use this incredible scientific knowledge for evil purposes. This sort of thing could easily get out of hand in the wrong hands.
But no one knows for sure what will happen in the future of cloning. We just hope that people use cloning responsibly and for the benefit of the human race.