When you choose someone to look over your admission essay, you should choose someone who will not be afraid to tell you like it is. In other words, don't just show it to your mom or your significant other. When you show it to someone who isn't afraid to give you criticisms then you are doing yourself a giant favor. Remember, those who review it when you turn it in will be looking not only for the good, but the bad as well. If your statement is not among the good, then it will get weeded out with the rest of the bad.
Just as a strong personal statement can get you in, a poor personal statement/essay can quickly eliminate you from the mix. When a medical school committee has a few hundred applicants, seeing typos, spelling mistakes or bad content will quickly move you to the bottom of the pile. The personal statement is a quick way to "weed out" similar applicants. With two similar applications, the personal statement can decide who gets an interview and who does not.