I tend to browse Amazon, then go to the company website.
So where, out of those two, are you getting unbiased information? Hey, reviewers aren't perfect, but they put less spin on a product than a company website. Also, reviews aren't the only thing the gaming press does, they also put up previews and consolidate gaming news so you don't have to visit a dozen individual company websites.
Amazon allows user reviews, which is great, but I don't see how those are more trustworthy than a gaming site. Heck, it could just be the game's developers posting about how wonderful their product is.