Just passed the Java 5 certification exam! I've been studying for the last couple months and very hard for about the last two weeks. I used the K&B book and lurked around here a lot. I didn't buy any mock tests but took the free ones with Whizlabs and Enthuware. I also took each of the K&B mock tests once, and was pretty worried because on Wednesday I got a 56% on one of the tests... Anyways, I scored 81% on the real test and actually thought it was kind of easy. Especially the drag and drop, I really thought those were the easiest because it was dealing with actual code usually. I had marked about 20 questions throughout the exam, but after I had gone through it once, just looked through the ones I marked and finished the exam, didn't feel like looking at the anymore!
So yeah, time for some more free time at night. I already have a great job programming Java, but they wanted to get some of us certified so all in all, this cost me nothing, except for a lot of time studying.