I did the first Kaplan Simulated Exam, I'm not sure how useful it will be for the real test (since everyone says Kaplan questions are nothing like it), but it was definitely a long test. I think it was helpful in the sense that I got a feel for what a 7-8hour test can feel like. I felt wasted at the end of the test, and I felt like I didn't do very well, but it ended up getting 75%, which was 10% higher than my cumulative kaplan Qbank average.
FWIW, I like the kaplan questions and I don't find them too detail oriented. There were a lot of questions that forced me to really think quickly and eliminate options and then guess (stuff I had not really seen previously).