According to user reviews in various places, like Metacritic, IGN, or Amazon, Modern Warfare 2 is one of the worst games in history, with a user review score hovering very close to the absolute bottom. At the same time press reviews regularly score the game above 90%, as one of the best games of the year. What's happening?
What is happening is that the press in most cases reviews the game just on the merits of its gameplay, and apparently MW2 is a fun game to play. The players meanwhile are very upset about issues not directly connected to gameplay: The campaign is too short (and downloadable additions will probably cost extra), the game is priced more expensively than comparable games, and the multiplayer mode is too restrictive. Thus large groups of unhappy players are trying to send a message by voting down the user review scores of MW2 on various sites. Something similar happened in the past to games like Spore, which were downvoted for their DRM, but with MW2 the practice of lodging a "political" protest against a game by giving it a bad user review appears to be expanding.
I've never been a fan of any review scores, but the more different issues you try to express with a review score, the less useful it becomes. I am not saying that the protests aren't valid: $60 for less than 10 hours of gameplay is expensive by any measure (and 30 times more per hour than I pay for MMORPGs). But by mixing measures of gameplay quality, price, DRM, and customer service into one single number, you end up with a number that isn't expressing anything at all. Different players have different degrees of sensitivity to things like price, game length, or DRM, so a score expressing everything is even theoretically impossible.
What will protest review score lead to? Amazon already got into trouble during one of the previous protests when they sneakily tried to remove the protest reviews from one game. If protest reviews become more widespread, people trying to find out about a game will learn to ignore user review scores. And sooner or later the sites now offering the possibility for users to review things will stop doing so. Sites like Amazon will decide that the protesters are hurting sales. Sites like Metacritic and IGN will decide that offering infrastructure for user reviews that are then ignored by the regular users, because they are held hostage by some protesters, isn't worth it.
And the effect of these protests on Modern Warfare 2? Apparently none, MW2 is said to have broken all first-day sales records, netting $310 million on the first day alone, with sales for the first week projected as being 10 million copies. Not bad for a game that score 1 out of 10 on average in user reviews.