OK the good about this photo is that you took a nice clear shot and did frame it up nicely with the trees. The bad, is that it isn't very interesting or compelling. I'm sure the concert was terrific, but we just don't get that sense from this shot.
Clever use of natural frames and the roof of the building.! I think I'd have liked to have seen a more defined subject. The band is slightly lost amongst all the other people.