In Nashville (2 July 2011) his voice sounded much better than when I last saw him (October 2009). The only time he had any trouble was in trying to hit the high note on "Miss Sarajevo." It was a challenge for him to stay hydrated because of the intense heat and humidity, and I think Bono knew he wasn't going to be able to sing that part very well. He took a swig of water right before it and hoped for the best.
But overall, I thought his voice was amazing. I wonder -- do you think all the rehabilitation he had to go through after his back surgery might have helped his voice?