The Wiz "No Bad News"
When I was a senior in high school, this was our fall musical. I had never seen it before my fellow thespians and I got involved in the production. As I was watching our stage show for the first time, I instantly fell in love with the music. Soon after, I found the 1978 movie at Best Buy and invested in it. My high school did justice :-)
Now, I say this musical is underrated because I don't hear a lot about it. Maybe it's because it was highly popular in the late 70's and early 80's. Maybe it's because it didn't get a lot of marketing. I have no idea. All I know is that more people my age (and in high school) need to watch this. The songs are absolutely brilliant and get stuck in your head for days (and, in my case, for a couple weeks). I am mildly interested in seeing a remake of this, just to see how it would look today. But... I'm too much of a fan of Michael Jackson and Diana Ross to see them replaced. :-)