A friend of mine once told me that there are three criteria that contribute to the quality of music. They are:
Pleasant to listen to
But in order to make the music good, it must contain at least two of the above elements. Therefore, for example (and these are my personal examples, seeing as it's all subjective anyway, so you may not agree with them).
Schumann's "Dichterliebe" contains intellectual content and emotional content, but for me it is not pleasing to listen to. However, I must concede that it is good.
J Strauss's "Blue Danube" contains no intellectual or emotional content, but it is pleasing to listen to, yet according to the above criteria, it is not good.
Gerhard Stabler's "Red on Black" has intellectual content (of a fashion), no emotional content (except tears of laughter within the audience, which the composer actually expects and appreciates) and isn't terribly pleasant to listen to. Therefore, one out of three means....not good.
Mozart's "Requiem" is filled to the brim with intellectual and emotional content, and is absolutely sublime to listen to. So I guess it must be very good.
John Cage's "4'33"" has neither intellectual or emotional content, neither is it particularly pleasant to listen to, due to the fact that you can't hear anything. So.... you know what the answer is.