Someone said very early on (I can't be asked to go find it again and quote the guy) that Yahtzee's primary tools are sarcasm (which may as well be second-nature to anyone growing up in this generation) and hyperbole. These are his gimmicks, and for what it's worth, he's better at using them than any other critic I've seen.
The problem with it is that in order to actually take his reviews as reviews, you have to cut through that to see what he's actually saying (or just read Extra Punctuation. He's not trying to be as funny there). Too many of the people in either extreme camp don't do this, and we get threads like this because of it.
If nothing else, a man that hates all games (again, hyperbole) is good for one thing. If he likes it, it's probably good. He's never made me NOT buy a game (with the possible exception of Darksiders), but I bought Psychonauts, HAWX, Portal, and Arkham Asylum (okay, I would've gotten AA anyway) because he loved them, and I was not disappointed.