I understand. Everyone is different. The first time I heard MErcy, i didn't like it all that much. However, on the second and third listen, it became clear that the song's chorus was undeniably awesome. The song doesn't have a cohesive flow, which is probably why U2 put as a b-side. It does have great lyrics and a chorus that won't escape from my head.
Listen to just the chorus and tell me what you think.