Why even call it Book of Secrets?
NATIONAL TREASURE: LOST CITY OF GOLD would've made more sense.
The actual Book is just a very small piece of the puzzle.
Don't get me wrong, I like the first National Treasure quite a bit. But this one was... well, scattered. Where as NT1 was clearly a treasure hunt, this one felt like it didn't know what it wanted to be:
-the journey to clear his ancestor's name (which, by the way, how did anything that happens in the last act of the movie clear his ancestor's name?!)
-the search for a lost city of gold
-and the discovering of the Book of Secrets
Now, if this movie were modeled more like the first --with one clear goal-- and was just a search to recover the Book, that'd make more sense.