I didn't really like the first one - the multiplayer wasn't particularly strong and there was seldom support for four players.
In this one, the ballance has been redressed. It's more of a part game than a minigame collection as the minigames are in groups of six, each themed around a continent (Europe, America, Aisia etc.) After each minigame, the players are placed first, second etc. and given scores accodingly. The winner is the one at the end of the trip with the most points.
This makes the game feel larger and more engaging than the minigame collections like Wii Sports because you are engaging in a tournament with your friends rather than just playing single game after single game with no one really keeping score. This does leave the players who are a bit rubbish out in the cold somewhat though...
The games are less inventive than they were the first time round though. The use of the wiimote is less exciting but then again, I think the games are of generally a higher quality. There are only 60 this time so there are fewer duds (although there are definitely some dodgy games in there). The humour has been stepped up a notch thanks to Rayman being sidelined by the Rabbids.
The single player game is pretty terrible however. It doesnt have any of the charm of Wario Ware and the only reason you'd ever play them is to unlock new costumes (of which there are almost a hundred). Actually, I'm being unfair. The minigames are still fun by yourself, they're just not as fun as they are when you're with friends.
It beats Mario Party 8 as a party game because, joy of joys, you can skip the cutscenes. The games are all slightly longer as well, which increases the sense of competition.
Overall, Rayman: Raving Rabbids 2 is a brilliant game if you have several friends who all love the Wii. The games are polished and often hillarious. The only things that let it down are a disapointing singleplayer and a few dud games. Because of the quality of the rest of the game, this really doesnt matter.