I just received the email from ISC2 that I passed the exam and now I am a certified security architect.
I sat for the exam last month. In order to study I used the official guide, and I bought access to the CISSP questions from cccure.org. My goal was to study the manual, and do the pro questions from cccure.org.
Besides the official guide I used some documents that were mentioned in the book, and I read again the related chapters from Shon Harris's CISSP book.
I can tell you that the exam is tough. What makes it difficult is that it goes deeply in VoIP, web technologies, wireless, and access control, which are not covered deep enough in the official guide. I found it to be difficult enough to give someone the assurance that the person who passes the exam has a decent knowledge about security architecture.
The official guide is not bad, but alone I don't think that will help you pass the exam. It tries to cover all the domains, but it covers perhaps half of the questions in the exam. The subject is so vast that you cannot cover it in 400 pages.
The dilemma with the ISC2 exams are the 25 test questions; are they the hardest one, the easiest one, or...? From the remaining 100 questions, you have do obtain 70% score in order to pass. So...
Also, because I wasn't clueless to any question, I might be wrong in my evaluation.
I think that the questions for the CISSP exam, from cccure, are not covering deep enough the material required for ISSAP. They have a different focus, as CISSP CBK is different than ISSAP. So, you can try them as a refresher, but won't help you very much for the real exam.
What I liked at the exam are that the questions will make you think a lot, questions like "which of the following answers MOST ...". For me the three hours were enough to go through all the questions and to revise some of them.
I think that my experience, and all the studies I have done for penetration testing, and security in general helped me a lot to pass the exam.