Everybody has them, and it is good to know that an applicant can see them and face them. DO tie yourself to the college and or program. Be specific about what this particular school or program can do for you. Your essay can have different slants for different situations. DO speak positively.
Negatives tend to turn people off.
DO write about your greatest assets and achievements. You should be proud of them. But . . . DO NOT repeat information given elsewhere on your application. The committee has already seen it and it looks as though you have nothing to say. DO NOT write on general, impersonal topics like the nuclear arms race or the importance of good management in business.