My favorite Star Wars movie is The Empire Strikes Back, but Revenge of the Sith is really good, too.
I agree with Al as well-Episode III did have some flaws that could've been fixed (like the script for one thing-some of the writing was kind of bad and some of the acting could've used some work.), but it was still an amazing movie with an excellent story, special effects, and was very emotional at times.
I, too, have heard the rumors about more movies and hopefully, this will end up to be true.
However, it probably isn't because I saw Lucas say in an interview once that after Episode III he was through. But if he did make a 7, 8 and 9, I don't think it should go past that.