Richardthebrave gave me some insights in the book, it has:
1. Team S profile (inc. Tsukina)
2. Team KII profile
3. History of SKE48
4. Performances of SKE48
5. Essays written by Team S members
6. Free "personal" letter of a random Team S member plus her photo
7. Miscellaneous photoshoots in the park
8. Focus on Sunshine Sakae mall
8. SKE48 merchandise
Sounds like it could be cool, but I still think it's too expensive for what you get.