A review is based on the writer's experience - it should convey not just the things you liked or didn't like about a game, but also how it made you feel. Feel free to clarify your biases, as that will help others understand some of your perspective.
Write anything you like, but keep it clean, and don't forget to check your spelling and your grammar before submitting.
We want to allow anyone to write reviews, but we reserve the right to remove any reviews we feel are excessively offensive, or are clearly just trying to skew the user review score.
Ideally, reviews should follow the same rating guidelines we use for our site reviews. A detailed description of these can be found here.
Lastly, in the immortal words of Wil Wheaton - don't be a dick.