I bought it and tried it on Friday, ended up playing for a fair few hairs so it's not to be sniffed at. There's some duff games modes in there where the gamepad probably should have just been forgotten altogether, passing it round just to roll a dice is pointless stuff but beyond them there's some really good and fun uses of the gamepad.
The two player gamepad only minigames are a nice change and something I'd like to see again and the basic Wii remote games are as good as ever for the party series. The games that use the gamepad alongside the Wii remotes are the bestt though, my favourite game is perhaps one where the gamepad player has to use it to look at their surroundings and describe where they are so the tv players can find them in a town of identically masked Miis, the game in which other player's have to guess your facial expression is also a hoot.