I don't know about platform bias, but GI has admitted to rating games based on how they assume their readers will feel about games, and I'm pretty sure there is some sales potential factor going into some of these reviews. Not that there is anything really unethical about speaking to your audience, but hey. I certainly don't put much stock in their reviews, but then I'm not sure I can name any review source I really trust to offer a balanced and reasonable buyer's guide.