Always loved this one too.
A couple years ago, German prog magazine 'eclipsed' compiled two Genesis top ten song lists, one for the Gabriel era and one for the Collins era. In the Gabriel list they put Dusk along with much more obvious songs such as Watcher of the Skies, Supper's Ready, The Cinema Show etc.. Later on they published an interview with Tony Banks which included his reactions on their list. It said he was horrified when he saw Dusk - "one of our worst songs!". He also said he wouldn't have picked Dancing With The Moonlit Knight, and asked why they left out Firth of Fifth. Tony being Tony, I guess. I'll have to find the magazine in my stuff to look up the lists in case anyone is interested.