This week's book giveaway is in the General Computing forum. We're giving away four copies of Arduino in Action and have Martin Evans, Joshua Noble, and Jordan Hochenbaum on-line! See this thread for details.
The type of questions is pretty close from what you'll see at the exam, but I think the questions are a bit harder. I think you can expect better results at the exam. I don't remember exactly how much I scored at Enthuware's mocks, but it was not high. I got a better score at the exam. The point is to carefully read the explanations of each questions.
Just took the exam and scrored 75% which is broadly in line with what I was scoring on the Enthuware mocks. The questions were pretty close to the real exam (I'm pretty sure one even came up that was virtually the same word for word!), all in all I think Enthuware are pretty good, I have used them for both SCWCD and OCPJBCD now and they have helped tremendously.