http://www.nintendo.co.jp/zelda25th/guidebook/index.html
The book is called Hyrule Historia.
It's 274 pages long.
Based on the table of contents, it contains:
Detailed Skyward Sword stuff broken into various sections: 67 pages
The World of Hyrule detailed in several sections including a timeline: 70 pages
Artwork for the individual games:
Legend of Zelda – 4 pages
Link’s Adventure & Link to the Past – 2 pages
Link’s Awakening – 1 page
Ocarina of Time – 6 pages
Majora’s Mask – 3 pages
Wind Waker – 10 pages
Oracle series – 6 pages
Twilight Princess – 32 pages
Phantom Hourglass – 4 pages
Spirit Tracks – 22 pages
The rest of the book contains an evolution of Link’s character designs over the years, a catalog of Zelda games, and some other extra stuff.
