Prometea, by all accounts, came into the world as a healthy animal, and unlike Dolly the sheep (the world's first cloned animal) has maintained her good health. So much so that she gave birth to a son, called Pegaso, in March 2008. It confirms that cloned animals can live a healthy life and reproduce.
That she can was seen by the scientific team in Italy as a demonstration of the benefits of reproductive cloning in horses. Namely that when sporting horses are young they are castrated, and if they grow up to be champions their genes are lost to the next generation. But if clones can be created, a champion's genes can live on. Rather than thinking of cloning as some science fiction evil, the scientists consider the reproductive cloning of horses to be an assisted reproduction technique.
Despite controversies and limitations of technology, there have been many other cloned animals and the technology continues to improve.