Just had a quick dip here and there into the concert on BBC iPlayer. Her voice isn't bad - just somewhat different than she sounded in her heyday, which isn't that unusual as singers age. She's 64 - an age I can relate to - and many singers' voices can change dramatically over 40 years. A prime example of age radically altering a voice is Marianne Faithfull. I have a CD of her singing at a live concert in a New York church in 1979 ("Broken English"), with a voice ravaged by life - and I think it's great! So I wouldn't classify Carly Simon's voice as appalling, any more than I think Dylan's current voice is appalling. Just older, more lived in, more interesting...

In the end, it's all down to personal taste - and beauty is in the ears of the listener.