If you haven't had someone else look it over, DO NOT submit it. I would recommend having 2-3 people look it over, preferably a colleague in your field (or related field) and someone who has applied and been accepted to a program. It's probably best to have a proofreader who knows you on a professional and/or personal level. They can help you add things about your experience or academics that you may have omitted and can help you develop the ideas you already have in your SoP.
Good luck!