By now you would have heard a lot about GMAT. So, what's so great about GMAT besides it being the dreaded graduate test that everyone who wants to do MBA (or some MSc, MA even PhD. requires)?
Looking at the bigger picture of GMAT, it has taught me a few things:
a. From Verbal (Sentence Correction), I learnt about the 3Cs - Correct Grammar, Clarity and Conciseness. My business writing has definitely improved tremendously after learning the 3Cs. Subject-verb agreement, parallelism, idioms, modifiers, etc. are emphasized in Sentence Correction; things we take for granted when we write but how power when you apply them correctly.
b. In Quant (Problem Solving), I learn to be quick in deriving answers. Those days in school, we take many steps to arrive at an answer. In GMAT, you use approximation/estimates, 2- or 4-steps to solve a problem and analyse the question from the right angle.
c. In Quant (Data Sufficiency), your mathematics/algebra principles and foundations are strengthened through how you tackle a question. Besides rephrasing the question, you look for variables that are important to answer the question and throw out red-herrings.
I must say I am pleased with what I have achieved through GMAT. I hope you too, will benefit greatly from GMAT than it just being a preparatory test for your MBA/Masters.