"It is an unflinching look at a grieving family in tough and striking language," Davies said.
Enright has described her book as "the intellectual equivalent of a Hollywood weepy".
"When people pick up a book they may want something happy that will cheer them up.
"In that case, they shouldn't really pick up my book," she said.
'Dark and unreadable'
The Gathering is a family epic set in England and Ireland, in which a brother's suicide prompts 39-year-old Veronica Hegarty to investigate her family's tangled history.
Enright has published three previous novels, two short-story collections and the non-fiction work Making Babies: Stumbling into Motherhood.
The Booker, which has been won by a string of renowned authors from Salman Rushdie to JM Coetzee, has been criticised for selecting dark and unreadable works unlike the winners of more populist literary prizes.
But Davies, defending the judges' choice to critics, said: "I think you people will find this a very readable and satisfying novel."
Among the favourites to win was Mohsin Hamid, a Pakistani writer, for The Reluctant Fundamentalist, which tackles the fears of a post-9/11 world through the eyes of a New York businessman.