GMAT experience

So I took the GMAT today.....it was a bit more challenging than I expected. What does the GMAT prove anyway? Is it that you can take a test with a time limit? I tend to get a nervous when I know I have a time limit, causing speratic thought. All I want to do is get into an MBA program, make the grade, and get a piece of paper that states I completed a program. Because that is all college really is, proof that you can learn! Needless to say I did not score as high I thought I could. Now we will see if I get into the program that I want.