I don't want to instigate any negative feeling but I insist that you be a bit careful out there. I prepared quite a bit for the Exam and my scores on GMAT Prep were 670, 670, 720, 720 respectively. I scored both of those 720's on the day before the exam. Granted there were few repeated questions but there weren't many (not more than 2 or 3).
I scored consistent 47,48 on Quant section and 41, 38 on the Verbal. I relied on a bit of luck to help me on the actual exam. I went in feeling good, started quant very comfortably, and felt almost like I was doing GMAT Prep Exam. There were some very easy questions in between but I didn't get alarmed. I wasted like 5 minutes on a question but comfortably finished the Quant section within the time frame. Verbal Section went well too and I was almost certain that my first 10 answers were absolutely correct. There were some easy RC's and some tough ones. I finished the section comfortably too. I felt confident that I'll see a 700 because the whole experience was not different from when I was writing the GMAT Prep. I must have guessed some questions but that was okay. On my GMAT Prep I missed 12 questions on quant and 7 questions on verbal but scored 48 and 41. Because of this experience I wasn't too afraid of getting some questions wrong.
Okay, after all this when I see my scores it was pathetic 580. Q 40 and V 30. I never scored 580 on any of my previous practice exams. Even on
MGMAT tests, which are really tough I scored 600 on my first test (with not much of a preparation).
I have no idea what went wrong. I really trusted GMAT Prep Exams way of calculating score but got screwed big time. I'm guessing the system must have decided my level on the first or second question and never gave me a chance to improve myself. It consistently gave easy questions below 600 level and even though I got them all correct it never picked up from there. I'm incredibly disappointed and currently not in a position to trust GMAT's so called Adaptive Exam.
Please let us know how it fared for you.