I'm pretty close to what delossantosj does. I basically look at all the aspects of the game, what was good and what could be improved (as well as HOW it should be improved) then give an overall rating. This way you break down the feedback into specific areas so the developers can get a sense of what's right, what needs work, what kind of work needs to be done, and the players reading your review get a clear idea of the game.
You'll want to divide portions of the review and give them certain aspects to cover, be it visuals, gameplay or plotline. You'll want to make these paragraphs ease into one another and make links between the two elements before elaborating your opinions.
Try and use synonymous words but at the same time don't reiterate over things. "The world is beautiful. It was so magnificent I cannot compare it to any other game." There is an example where I've used the words beautiful and magnificent, that was not necessary, the last words could have been thrown onto the end of the first sentence and it would have been a much easier read.
Don't digress onto insignificant aspects to the game but do pick out things that stem from the campaign or story that you really enjoyed or disliked. For example, you could explain how the cut-scenes added a lot of depth and got you to engage with the story, but also note how map design in the multiplayer really turned you off.
Don't use spoilers but extract examples from your experience and use them to give evidence of the certain bullet-points in your review. "I love the balance of weapons [insert personal example here]." Furthermore, don't swamp the review with examples use one or two concise narratives to draw attention to the things you liked or disliked the most.
Realise your audience (important in any literary work) and write for them, adjusting your vocabulary, eloquence and length of the piece.
If you want to Holden, log onto 201's website, and I'll give you some real-time assistance there.
