After putting the exam off continuously for about 18 months, I actually got around to taking my Zend PHP 5 Certification exam. I originally scheduled the exam, put it off for a few months, then actually forgot about the exam altogether, only to reminded by google calendar an hour before I was due to take it. The test centre was at least an hour away, so that was a waste of $125. I scheduled the exam again, kept putting it off until I caved in last month and got it done.
The exam itself was considerably harder than the original, I wasn't all that confident when I clicked the 'End Exam' button, but I got the job done. I'm glad I found it harder, I've obviously improved my knowledge of PHP since I took the original exam nearly 3 years, so they must have made the certification more difficult to achieve.
As far preparation goes, I read the study guide right through once, making notes along the way. I turned up at the test centre about 20 minutes early and went through my notes. The study guide clearly did a good job!