The five paragraph format was used in high school to help you get a hang of writing an essay, plus its a very boring format. You should be more creative with your personal statement and use whatever format you think best fits what you are trying to write about. But just as with any other essay, you should still have a thesis statement so that your essay will be more unified and coherent, an attention grabbing introduction, and a concluding statement that brings the rest of your essay together.