Prudie - "ABBA always get a snub as being musically naff but in actual fact their songs are quite complex and very hard to sing - as has often been proved in X factor etc etc"
I have always smiled at the historical re-imagining of Abba.
Here in 2014, Abba are about as cool a pop band as you could find anywhere, but history has been very kind to them -
Back in 1979, Abba were the Westlife of their day, Naff City, and not to be mentioned by serious music fans for fear of terminal credibility damage!
But as you rightly observe, their songs were gems of pop sensibilty with deceptively complex arrangements and harmonies, proven by their longevity and ongoing popularity.
When Abba The Musical was being designed, they had to draft in transscribers to score all the music - Benny and Bjorn do not read or write music, so everying was done aurally, and never committed to paper.