So after taking 6 practice exams and passing them all with varying results, I decided the best way to prepare for the exam was to take it and study on the failed areas.
Well, I passed the 70 question exam in 31 minutes due to 1 or 2 trick questions.
IMHO, they could have made it a bit harder. There were no questions like "What does echo NULL + 0x20 display?" It was mainly over language constructs, flow and output. It was about 50/50 with OOP. Most of the OOP questions dealt with XML (SimpleXML, DOM, etc) and PDO. Not a single MySQL question and only one MySQLi quetion, which isn't too surprising since MySQLi is a PHP5 thing.
If you're looking to pass the exam and know most things about general PHP (OOP, references, declarations, type hinting, casting, etc...), study XML parsing, PDO and MySQLi and you should pass without issues.
So my lads, fear not the ZCE exam, make the ZCE exam fear you!