How important is the first page of a book?

Self-evidently, the opening  is crucial, few of us buy a book without reading at least the first page.

I have just begun The Hundred Year-Old Man Who Climbed Out of the Window and Disappeared.

Far too early to say if I’m going to enjoy it, but the opening page is brilliant:

“You might think he could have made up his mind earlier, and been man enough to tell the others of his decision. But Allan Karlsson had never been given to pondering things too long. So the idea had barely taken hold in the old man’s head before he opened the window of his room on the ground floor of the Old People’s Home in the town of Malmköping, and stepped out – into the flowerbed. This manoeuvre required a bit of effort, since Allan was one hundred years old. On this very day in fact. There was less than an hour to go before his birthday party would begin in the lounge of the Old People’s Home. The mayor would be there. And the local paper. And all the other old people. And the entire staff, led by bad-tempered Director Alice. It was only the Birthday Boy himself who didn’t intend to turn up.”

Everything you could want: intriguing, original and bizarre!