I remember coming to see a performance of 'On the Town' and not knowing much about it, didn't know what to expect.  It was exhuberant and fun - OK perhaps not the most tightly plotted of pieces, or the best story in the world but what mattered was that the performers and orchestra really looked like they were having fun - and it was infectious.  By the end, all that mattered was that everyone was happy, living happily ever after, with some great songs thrown in.