Macfarlane said the novel "requires a huge investment from the reader" but delivers big returns. "It begins in fixity and then it accelerates out of it, and once you are on the down slope, the pace is irresistible," he said.
He said it was a book that "takes place in a culture which is utterly capitalized" and focused on money, but also dwells on tenderness and love.
Macfarlane said the panel of five judges met for two hours — brief by Booker standards — to choose the winner, which was decided without a vote. "No blood was spilled in the judging," he said.
Catton, who was 25 when she started writing the book and 27 when she finished it, has published just one previous novel. Now she has won a prize that brings a huge boost in profile, publicity and sales, and whose laureates include V.S. Naipaul, Margaret Atwood, Julian Barnes and Hilary Mantel.
The only previous New Zealand winner is Keri Hulme, who took the Booker in 1985 for "The Bone People."
This is the last year that the Booker — founded in 1969 and officially named the Man Booker Prize after its sponsor, financial services firm Man Group PLC — will be open only to writers from Britain, Ireland and the Commonwealth of former British colonies.
Beginning next year, Americans and other English-language writers will be able to enter as well.
The rule change aims to expand the global scope of the Booker even further, although some fear it may alter the delicate chemistry of the prize.
Macfarlane said "The Luminaries" was a fitting winner — "a global novel that is always intensely local."
And its sheer size — eight times the length of Toibin's 104-page "The Testament of Mary" — had an added benefit for the judges.
"Those of us who didn't read it on e-readers enjoyed a full upper-body workout," Macfarlane said.