Yes, there really isn't such a thing as a bad U2 show. That one just happened to be the worst one I've seen. What is it with U2 and their opening bands always being crap? The other time I saw them at Tampa stadium, they had Los Lobos for the opener. Los Lobos and Public Enemy? Yuck. I did see U2 at curtis hixon hall back in the very early 80's and the Alarm opened for them. That was the best U2 show ever and the Alarm was a pretty solid opening band.
Hey they had the Killers open for them some on the last tour. I've seen the Pixies (Lakeland), No Doubt (Vegas), and Keene (NYC) open for them. I also saw a local band open for them in Atlanta becasue the opening acts' singer got sick (imagine that, you get a call and somebody wants to know if you can open for U2). I think they like to switch it up. Show diverse nature of their fans.
Zoo Station was the first tour I saw. I was too young for that Curtis Hixon show (a friend of mine's older sister has a play list from that show. Roadie lifted it right pff the stage and handed it to her after the show) and the Josua Tree show here was just before I started going to concerts.