Passed my ITIL Foundation certificate today. Scored 85%  in 25 minutes. Took me 1 week to prepare, used exclusively ''ITIL Foundation Exam Study Guide'' by Liz Gallacher & Helen Morris which is very good book imo.
Overall wasn't impressed with the test..... because these kind of tests you probably have in high school. Very easy and there is so much room for error (65% is passing score) that it's hard not to pass. I can't compare how tough were Cisco exams and how was this one. Basically if Cisco exams has the highest failure rate in this indstry then ITIL probably has the lowest 

If my english language would have been native, then I guess I could have prepared even in less than week. Additionally can say that working already in work environment wthich uses ITIL framework helped to understand the principles better.