Imagine if you took home a Mario Party game and invited friends over to play, only to find that you have to unlock all the mini-games by first playing through single-player. I think this is a huge problem, as is the limited number of simultaneous multiplayer mini-games, and that's why I think Obi's review rings true. Clearly he admires the humor and the multiplayer appeal, but the unlocking hurdle and repetitive nature are real issues. And, as Evan mentioned, this is still a good score -- just not a fantastic one.
I think some of the backlash to our "harsh" reviews of launch games comes from the fact that some people are enjoying these games simply because they enjoy playing the Wii -- almost regardless of the game itself. It's an understandable side-effect of launch mania, and hey, if you're having fun with every single game, that's awesome. But we do have to look past hardware romance and judge these games on their own merits, and the truth is that many of the Wii launch games are mediocre but are made more amusing (to varying degrees) by the nature of the controls on Wii.