Slow down there, it's not that good. It only counts spell cards used after it's activated, so you can't just drop it at the end of the turn a get a bunch of plusses. However, and hand Judgment+Spellbook of Secrets + any third Spellbook will easily set up a High Priestess summon the next turn and the potential maximum benefits get a little crazy.
But because searching for it is like the worst thing ever, I expect people to play three copies in the hopes of drawing into one before they make any big play. Which I guess will be balanced out by all the Judgment/Life/Eternity hands people will be bound to get.
The thing is that whatever it happens, it lets you choose from the deck, and it quickly becomes a +1 or a +2. Whatever card that triggers the "activated a spellbook" is good in my books.
Let's see, a power play:
normal summon fool (send 1 to the grave)
activate judgement (2 books in grave)
activate secrets, search for book of the master (3)
master, search for power, activate power (4)
search for wisdom, activate wisdom (in case of awesome battle)(5)
end turn: tribute fool, bring reaper, 5 cards with different name, special summon a delg or destroyer. search for 4 books to hand. done.
don't know you bro, but first turn "that" is a lot of advantage.