As far as I am concerned, I really liked JQ+. At first I took the tests exam-wise, that is, 59 questions in 2 hours, but then I noticed that some questions were coming back again and some never.
So to get the real value of what I knew of
Java from the JQ+ perspective I just customized myself a nice test of 700 questions and took it several times. All questions together, from very easy to real brainer, everything in the same bowl. It took me some time to finish (but since time is not an issue in the real exam, I didn't pay much attention to it.) but the percentage I got was actually the real JQ+-percentage, some percentage you can seriously think about, and not a nice 99% because you have seen the questions four times already.
Anyway, if you plan on spending a good deal of time on JQ+, it's worth it.
My $0.02