There is no such thing as an impartial "essay company reviews" site.
Oh yes there are. ES is one of them. There are trustpilot, sitejabber, and other independent review sites that allow actual users, and shills to post reviews, both positive and negative about a certain company. Those are the most impartial reviews you can get. Although a bit clouded due to paid posters, the negative reviews are what the student should be looking at as those are the most accurate reference points for the service. Paid negative review or not, the more negatives there are in the review list, the more possible it is that actual students have written the review.