The SAT essay is read by real people, but there are certain things they look for when they grade the essay. Use all the space given, use big words, and stay on topic with good examples.

A good example does not have to be a factual one, but one that supports your thesis. Take a read through this article on the SAT Essay:

http://www.applerouth.com/blog/2009/06/01/in-praise-of-folly-writing-the-sat-essay/