I used the BOK, and the new ISC book of 1000 practice questions.
I took the CISSP 12 years ago and still have PTSD from that! (Not really, but that was the worst test ever)
This was the next worst...really! My problem was the lack of detail in the question followed by detailed answers
I also have CISA, CISM, CRISC, & CEH. They were all easier than CCSP.