It's a little daunting to try to find something original to say about an album like The Joshua Tree. Released in 1987, The Joshua Tree sold something like 25 million copies, While it's no Rumors or Thriller, The Joshua Tree has been rather thoroughly reviewed many times over.
I was aware of U2 before The Joshua Tree, but I couldn't say that I was a major fan of the band. But when The Joshua Tree came out in '87, it really couldn't be ignored. It was all over the radio, MTV, and appealed to kids my age as well as aging boomers trying to keep up with current music. (Boomers who were probably younger than I am today, I might add. Sigh.)