I've loved The Wiz ever since I stumbled across the OCR and begged my mother to let me buy it. And when I begged her to take me to see the original tour (I did a lot of begging as a kid), I loved it even more--and so did she. I didn't care for the movie (poor Mom actually went and sat in the car rather than see it through), but I recently saw concert versions at both 54 Below and at SummerStage, and I love it still. Neither of the latter made use of the book, of course, and I
Stratas famously missed a lot of performances at the Met due to illness, but I don't recall hearing that she missed performances of "Rags" (of which there weren't that many anyway). Of course, I could be wrong.
I only ever heard positive things about Stratas's behavior (including from someone in the show).
There was much to like about it, including some gorgeous music--and singing--but as Wilmingtom says, there seemed to be a good half dozen plot lines. But Stratas, Kuhn, and Kert were all wonderful, I thought.