I have the CISSP but from a few years back now, 2001 I think. Still certified though
I remember piling all the books required on my desk and it almost reached the roof. The best approach is to find one good book for each of the 10 domains and study that. So typically around 10 books and then a CISSP Study Guide for focused refresh at the end.
This is a tough exam and requires long hours of study - just to get through the material.
The ISC site normally lists the recommended material BTW. I used forums to narrow it down to one book per domain.
Wrote it a good few years ago. You need to read read read and read some more. Its not difficult, it just requires tons of reading. Get your hands on as many books as you can. Also the Shon Harris DVD series if you can - they are great.