Ok I don't have much time..
First off I want to say that I am no genius I did the Manhattan GMAt course and it was good but Master GMAT is a different cup of tea, I gained 150 points from them. I REALLY hope they go GRE because my brother is going to do that later this year as he wants to go into foreign policy.
The course is really tight, it adapts to your weakness and each lesson is beautifully laid out, the English section is BY far the best explain of any material I had but gains were particularly from the Quant. I am not good at math, after doing GMAT TWICE I had a huge aversion to it, master GMAT broke the quant down to apoint where I felt "Wow I am really understanding this" even when I got things wrong.
To be honest I wasted ALOT of money on GMAT preps even while starting Master GMATs course because I lacked confidence in them (a year ago) and people (beat the gmat included) were going with the bigger names. Eventually, I reached a point when I said @#$^ it and plunged into their course (I got reminders from their system lol that I was away more than 30 days) and it was not a day that went by that I regretted not trusting their program from the beginning.
BTW I am a Entrepreneur I spent almost $3000 of my money on GMAT, a library of books and I am at this moment Master GMAT's biggest supporter in the GMAT arena, they really nailed it.
All the best.
EDIT: I will try to return but I don't visit this site much last time I came was probably 4 months ago, I think I have coupons or might have deleted it (no use to me really) pm me and I can send it to you if I find them will try to reply by the end of the week. All the best guys and keep the faith!
GMAT aint the end of the world.
Every Change comes from an action but not all actions lead to a change!