While there's certainly fun to be had in the multiplayer modes of WarioWare, they all seem pretty forced. In particular, Othello with minigames is a bit of a stretch. All in all, the minigames are the real star of the show, and they're great enough to stand on their own without needing some sort of external shell or other impetus to play them.
Graphically, WarioWare for the GameCube looks like the Game Boy Advance version of the game on a Game Boy Player. The same graphics are used with the same slightly blurry fidelity you may be familiar with from the Game Boy Player. Yes, there's definitely a charm to those graphics, but taken in the context of a game that already appeared on a handheld last year, the look of WarioWare on the GameCube feels like some sort of cruel joke. Making the contrast even starker are the non-game graphics. Everything from the elevator that separates minigames to the screens in all the multiplayer games is razor sharp, extremely colorful, and really quite charming. Then the minigame opens up, and you're looking at a blurry GBA game. The constant back and forth between the two makes the GBA-quality graphics look worse than they really are. It would have been pretty sweet to see the games themselves spruced up in a similar fashion.

The multiplayer focus of WarioWare seems a little misguided, as it takes some of the spotlight away from the fantastic minigames.
The sound in the game also comes from the Game Boy Advance version of WarioWare, but some of the music has been cleaned up a bit. The game's music and sound effects speed up alongside the action and really do a fine job of adding to the manic, pressure-filled feel of the minigames.
The manual for WarioWare Inc.: Mega Party Game$ is written as if it were Wario's diary. The first blurb ends with, "I'm feeling generous, so I'll even let you keep peeking at my supersecret journal to get the inside scoop on my latest scam...I mean, game!" After playing the GameCube version of WarioWare at length, "scam" actually seems like a fair description, though a harsh one. It may be retailing for only $30--the same price as the GBA game--but if you've already played the GBA version, there's little more for you to see here. And if you haven't played the GBA version, you're better off getting that one instead, as it achieves a certain level of purity that the GameCube version lacks. Finally, if you're a fan of multiplayer party games, you'd probably be better served by any of the recent Mario Party games.