His words do, but not his opinions. For example, I am able to deduce what gaming aspects or scenarios he's talking about without playing the games he reviews because he pitches them like a gamer would. I am able to somewhat get what the game is about at the end of the review, but I don't confuse his taste with mine.
For example, I wouldn't be buying Jericho because of his review- namely his description of the fight scenes and the general storyline (including the convolutions), knowing that I don't like that gameplay. In this case, I agree with Yahtzee.
I disagree with him on the matter of how much content should be spilled out by the game, namely by Mass Effect. I am an RPG lover and I can eat a good background and story with salt and pepper. For me, the fact that characters would involve me in their business or reveal to me their back-stories is great as long as its done with a discrete execution. In this case, I disagreed with his taste, but that's no criticism. It's just an observation.
So, yes, his reviews actually do matter to me. They serve well in scouting out games that might be potential buys. I haven't played most of the games he reviewed, but I do own the Orange Box, Psychonauts, and have played lots of Burnout: Paradise, and I totally agree with what his taste is on these, except for Ep. 2 toward which he seemed indifferent, while I thought it was a better game than both Ep. 1 and HL2, excluding game length from the equation. Overall I find myself loathing the average Japanese RPG and redundant, repetitive button-mashing, along with a bunch of other now-familiar Yahtzee pet-peeves. So, even with what I've said, my opinion does seem to concur with his, mostly. What's important is to know what one wants from a source of information and amusement.