Ocean's Eleven, is far far better than the 'Ol' Blue Eyes' original. Most of the time though, remakes are not as good.
There are too many remakes of successful films, and not enough remakes of films that really deserve one. There are films which had some good ideas, that just ended up being ****. Those films are hardly ever remade into good films though, because it's just not profitable enough. As we know though, it's always about the money.
Well it makes sense that they would only remake good (and successful) films as these are more likely to make money. Ironically these are the films that don't really need a remake!