This was a concern I had when i was applying, but now that its all over i can tell you essays are there to help you. For those of you who don't have much as far as extracurriculars go this is your chance to show the ad-com that you are a 3-D candidate. They want to see you through your essay. At many of my interviews, i was told my essay was very good, and asked if i received help writing it. When i told the interviewer that i wrote it and wanted whoever read to see me through the essay they were impressed. For those of you who have a lot of stuff (good scores and gpa etc) a well planned and HONEST essay will make you shine. And for those of you who had difficulties along the way the same applies to you. Perhaps you can show how you overcame obstacles and triumphed. Remember those applicants who demonstrate they have more to offer generally get interviews, put your best foot forward.