I don’t know that I’d classify it as either Christian art or blasphemy.
Some of it depends on how you do the show. I had a friend in college who had seen the show (in Germany I think) and they ended it with Jesus, Judas, and Mary Magdalene all getting on a Harley and riding off into the sunset. But when my (Catholic) high school did the show (I was an apostle ), we tacked on a Resurrection moment at the end so that it was really pretty moving.
I do think there are weaknesses (such as the lepers scene and “I don’t know how to love him”). But none of the weaknesses are so detrimental that they make the show inherently “blasphemous.” Though I don’t doubt that certain specific productions of the show have been blasphemous.