If Yahtzee likes a game, it's got to be good. He loved Portal, and Team Fortress 2, so I went out and bought the Orange Box for the PS3, and loved it (Minus Half Life, I hate it). If he had not so highly praised the game, I would not have bought it.
On the other hand, there are games he has bitched about that I have still bought, becuase I knew I would like the game. After all, his job isn't to inform us about games, it is primarily to entertain, and bring visitors to the website, enhancing profits from advertising therefor making The Escapist money. Where was I going with this again?
Oh yeah, some of what he says makes a lot of sense, but some things you can take with a pinch of salt, it's all about deciphering what aspects of his insults towards games will affect how YOU feel about the game.