yup. i took a few of them. my experience was that the math was super difficult and somewhat unrealistic -- the hard questions took too long to calculate. but MGMAT is conceptually more difficult and more of an IQ test (more like the real GMAT). the 800score verbal was rather nuanced and especially the reading comp tone questions were somewhat off. the sentence corrections q's were good, and critical reasoning wasn't terrible but again something funky about their logic. Once I got the nuances of the verbal down (learned how they were testing after 2 practice tests) my verbal went from 70% to 99%. shows you how effective their testing technique is ...
the overall scoring for 800score is not very consistent (or maybe I wasn't). my range was 670 to 740 and I didn't see much correlation between content mastery and score improvement.
if you want a more accurate test, I suggest power prep or gmat prep, the actual mba.com tests (old and new). MGMAT is a nice difficult test that should give you a fair idea within 30 points how you're doing. the math is purposefully more difficult than what you'll find on the real thing. verbal is pretty accurate, except very catered to the tricks they teach you, so you'll see some score inflation there. just make sure your SC is 100% solid -- no reason to miss any of those, even for non-english speakers. it's like basic math.
if you've used up all your MGMAT / Gmat Prep tests, try Princeton Review
. You can get 5 tests for $40 and the verbal is exceptionally accurate. Math is a bit too easy but they score harder to compensate. I scored 690-740 on these tests.
i just recommend you stay away from kaplan
. i took one of their practice tests, got a 620. i missed 5 questions total between the two sections. they were trying to scare me into taking their course (free diagnostic test at kaplan
center). they have many many flawed questions and scoring algorithm is wack. took a MGMAT test the next week and got a 740.
My MGMAT tests went from 550 - 750 over 6 months. My actual GMAT score was 710.
Do a blend of everything, test consistently, get your timing/guessing technique down and stick to it, and when you see an average score (between all tests) in the range you're shooting for or slightly above, take the real thing.