I am going to pass on this one. I refuse to support any games that don't run in widescreen.
Also, as minorthr said, the reviews have been pretty bad:
IGN: 5.2/10
All of our complaints about previous games – the slow pace, the lackluster single-player affair, the loose attention to detail – all remain and with Mario Party 8 we can add another criticism: ignorance of the Wii remote.
GameSpot: 6.5/10
The Good: Plenty of minigames; some inventive boards.
The Bad: GameCube-caliber graphics; spotty widescreen support; chance still plays too large a role.
1up: 6.4/10
Mario Party 8 could've used a lot more of that creativity, however, throughout the whole game. Instead, we get a really disappointing (but, as mentioned at the start of this review, inevitably still entertaining) Wii debut for the series. Perhaps the next game will truly take advantage of the Wii controls through and through.
GamePro: 4.5/5
Pros: Yet another dose of the sweet and simple Mario Party fun that everyone knows and loves.
Cons: Games seem to be decided more by pure chance than skill. Things can get a little boring in between turns.
AdvancedMN: 4.5/10
It’s Mario Party – but the mini-games feel thrown together, lacking any kind of inspiration. The number of maps/game boards is a bit low.
Nintendo Power: 7.5/10