Okay, as a general rule I stay away from internet forums of any kind because all my Baldur's Gate experience has taught me never to go into a room fool [Edit: oh dear, Freudian Slip..] of trolls without several fire arrows , but I felt oddly compelled to register and chip in on this debate because I really do sympathise with the general gist of the diatribe against multiplayer-centric games, and I think that Yahtzee could have come up with a few more valid points to further his argument.
First of all, people continually calling him on the last point should perhaps consider that he has characterised himself as a misanthrope in every review and article he's ever written, so you needn't become so incensed and consider it a personal attack on you - it's like the old joke: "I'm not a racist, I hate everyone equally". Personally all the misanthropy makes me chuckle; it's like reading a novel by Louis Ferdinand Celine. I think you have to take it primarily as hyperbole, but at least concur that it has some grounding in the premise that most people act like dicks when they can't see the other person - and for some people the oozing satisfaction of topping said dicks in the scorechart is reason enough to continue playing, but there are those of us who would rather just walk away and hang out with some interesting people. Not everyone is actually a jerk online, of course - but that's not reason to aggressively pummel someone into forming a more favourable opinion of a game because they don't have the time or energy to play it long enough to find enough players who aren't selfish pricks to form a clan - or whatever you call it these days.
Which brings me very neatly to my next point - one I'm surprised he omitted - that the multiplayer experience is really only what individuals make of it. MMORPGs aside, multiplayer components generally retain the same weapons, environments, core gameplay and artistic themes of the singleplayer portion of the game - so if one is going to review it, any comments about the handling of certain weapons, the appropriateness of the levels etc aren't going to be that different from the opinions formed in singleplayer. So essentially you can already apply much of his review to the multiplayer - what is missing, and what I presume leads many people to complain that he neglects the multiplayer aspect, is an assessment of whether the game is fun to play against humans instead of AI opponents. And really, this experience is generally so variable that it would take many many hours to form a reasonable assessment. When I was a zit-faced youngster playing the original CoD, one game on one map might see me having endless fun sneaking and sniping; I'd come back in an hour on the same map and the action had degenerated into a grenade spamming melee. So if a reviewer with little time on his hands happened to slip into one of those games and spend all twenty minutes being spawn killed; he'd probably decide the multiplayer wasn't worth it. It really comes down to who you play with and what you personally make of it. The game that probably stole the most hours from the time I could otherwise have spent writing angsty teenage poetry was actually Warcraft 3 - but not Blizzard's actual, official multiplayer, I used to play all the crazy 3rd party maps people came up with - and it was a lot of fun.
My point is that reviewing multiplayer is so subjective that it's ridiculous to expect a review which comes out within a week of the game's release to be able to tell you whether it's fun or not. Besides, a few tweaks in a single patch can so radically change the experience and result in such an exodus that you can't write a review that will give a lasting impression. I'm sure all the original reviews of WoW made something of the game's massive environment; nevermind that now you spend most of your (not mine, I jumped that bandwagon long ago) time in the same four or five zones. So really, if what you're after is an opinion, talk to someone who has the time to regularly play it, or better yet play it yourself, and remember that ultimately, it's what you make of it, so if some jaded British misanthrope in a hat doesn't like it you shouldn't really give a toss. That's my two cents - take it with the grain of salt that I don't really play multiplayer anymore, or even games of any kind anymore as I have to devote my time to being a literature nerd at university, and the only reason I even watch these reviews is because I get a raging hard-on every time Yahtzee references Proust or Dostoyevsky.