Don't listen to the 4.5 score. Sonic Shuffle did NOT deserve that.
Sonic Shuffle is basically Mario Party in a different structure of play. Instead of rolling dices, you pick out cards with a number. Then you go that number of spaces. Instead of the mini games coming at every single turn, you have to go to the Mini-Game space in order to acess it. Once you do, you're in for the fun. The only disapointing thing about Sonic Shuffle is the annoying battle systems. Also, the load times tend to get annoying at times. But other then that, it's all cool.
Graphics:
Outdated cel shadded graphics, i'll tell ya that. Sonic Shuffle just isn't as good looking as games like Jet Grind Radio. The framerate slow down is quite common in certain areas of the game. I hate to say this, but Sonic Shuffle isn't even good enough to be a good looking Dreamcast game.
Sound:
The music is not bad. It actually fits in with each level, and events. The voice acting is okay. Except there's a problem with Knuckles. In the Cutscenes, he's in a temporary voice witch makes him sound a tiny bit like Sonic, except in a low way. Then, in the Gameplay, he's back in his Sonic Adventure voice.
Conclusion:
I admit, there are some disapointing flaws in Sonic Shuffle. But, if you know how to go with the flow, you might enjoy Sonic Shuffle. If they do Sonic Shuffle 2, i'd make a few suggestions to them on how to make it better. Overall, Sonic Shuffle is a slightly below average party game.