The real difference between Mario Party 7 and this is the number
You're taking a visit to the Star carnival, which is run by the trio of MC Ballyhoo and his talking hat, Big Top. If you were to be an adult, this would start to feel like a game for 3 year olds. You are given a menu to choose which mode, none of which are new to the franchise, even after years of producing games in it. You have a nice widescreen format when you are choosing, which awkwardly goes away when you start playing the actual game.
When you are playing, the presentation is crappy. There is no widescreen. It's just a square screen that is bordered. The graphics aren't even any better than Mario Party 7. The text is just plain. Nothing to say, "Hey! This is a fun game to play!" The boards are no better than ever before. They seem to be recycled from previous games that might not even be in the franchise.
The gameplay still relys on chance. The minigames aren't going to help you. Cross your fingers because that's all you can hope for, luck. A little common sense still helps, but you probably won't rely on your game skills to help you win.
Speaking of the minigames, they are very good. While they use old techniques and don't take advantage of the Wii remote capabilities, they can still be fun to play and can help you make someone do the in your face dance. Some of the minigames, you pretty much can cheat on, like walking on the rope, just get a flat surface and keep your Wii remote flat there. But don't worry about that, worry that you probably won't get the chance to play all the minigames.
While Mario Party has never screamed, "Buy Me!" to any gamer, it has been a good party game, especially if you are lucky enough to get a bundle. It's most fun when you have some friend, but it'd be best if they were also fans of Mario Party. While a normal gamer would turn their back on Mario Party 8, it would take a real dedicated fan to buy it. It doesn't seem that Hudson understands completly that there making a game for the Wii, not the Gamecube. The series hasn't really evolved much, but that is no excuse. If your excuse for buying it is because of the minigames, make sure you have plenty of time. Those will take a lot of time and patience to find.