The big difference that divides people's opinions on this song is which tone people prefer. It's either the tone which hints towards insanity, or the tone which tilts towards depression. And personally i prefer having a tone of madness, especially In a song called "Mad World", although the depressive tone does work as well. To be fair, I'm not putting my all into this comment, but hey, this site makes you comment if you want to post it.
It is really good. It has such soft undertones and sounds beautiful. It really makes you feel the sadness of the song. It is not truly about madness, But about the idea that continuing in a world much like a machine is in a way mad, But we all participate every day. The sadness works better with the song.