I have listened to both. When the remastered version came out I bought it immediately because I had always felt this album was not very well recorded and so was eager to get a remaster--actually this goes for many U2 albums. Conclusion: It is better than the original but not by much.
This suggests that either Joshua Tree was not a very good recording to begin with, or, the remastering was just poor. I am guessing it was the former, but this is all speculation. Get the remaster but don't expect a night and day difference.
