Well, Yahtzee's very clear that his reviews aren't supposed to be in any way objective. So as long as you don't take them as objective criticism, that's fine. In a review of a game I've actually played, I find that the things he picks holes in are the same things that bugged me. And then, well, I already have an opinion. He'll say something is terrible, and I'll have noted it and judged for myself whether I consider it noteworthy. He sure as hell ain't going to convince me that Smash Bros Brawl is bad, although he did correctly pick up on some issues. The dude who owns a game is always going to be better at it; there's not really much a developer can do to solve these problems while keeping some kind of compelling skill curve. If I recall, Yahtzee blamed it on the unlocking system, but really that's not right. If there was nothing to unlock, the owner will still be more experienced with any game people might want to play, because he wants to play it.
Anyways, I digress. If, on the off chance, he reviews a game I might buy, I do think it's worth noting what he picks up on. There aren't a lot of reviews around that focus on what the developers have done wrong. Most reviews tell me how a game is awesome, and gloss over the problems in favour of 'excellent game, held back by some minor niggles'. Yahtzee, on the other hand, picks it to pieces and then might say 'given all that, it's still pretty good'. More often it'll be something along the lines of 'It's passable if unoriginal, and a useful purchase for people who want to play God of War but for some reason cannot own God of War'. Honestly, I find that more useful. Of course, me and Yahtzee, we do not look for the same thing in a game. I ain't interested in epic story and all that jazz; I don't want to be made to laugh and cry in turns. It is all about action and sometimes spreadsheets.