I guess we get the star ratings from overall feedback about a game, compared to how long it's been out and the amount of time it takes to plat compared to how many people have it? Take a look at something like Uncharted or Hannah Montanna. Hannah is very easy to plat and takes almost no effort in the long run (so it's one star), while Uncharted isn't that difficulty either but it does take some effort to clear it on Crushing (hence why it's 2 stars). Then you have games like Cross Edge and Red Faction, both of which aren't entirely that difficult but take a LONG time (hence the 4 stars for both).
Without having played every game on the list, it's tough to nail down the ratings for some games. For instance, I think DW Gundam 2 should be 4 stars, instead of the 3 it's at now. While you could play on Easy for most of the game, there around about 20 or so missions that require you to play on Hard and they definitely take some skill to finish. But I guess I could see the reasoning behind the 3 stars though.
