I agree that considering your whole profile and application package that you can't afford a cliche personal statement if you don't have other stellar attributes. However, I think that it's OK to have a cliche essay, because while details differ, there are only so many themes that the readers will already be so familiar with. So, even if it's cliche, it absolutely has to be well-written and well-thought. Many people have similar numbers; the statement is a way to personalize and humanize your application. It's an opportunity to make yourself stand out from the rest of the field and get the reader to think "I'd like to meet and talk with this person."