<p>I don't think that even 800 words is necessarily too long. It really depends on the essay. If it is very good and engaging, the reader will not mind. However, the risk you take is that your essay will not be amazing and you will bore the reader. </p>
<p>I wrote an essay that I felt came from the heart and I could not edit it down much; the content was not superfluous. I emailed my admission officer and expressed my concern that I wanted to respect their word limits, but I felt that the person I am best came across in my long essay. His response was that the long essay was fine if it gave them a better understanding of me as a person.</p>
<p>Hope that helps :)</p>