It seems to be a pretty solid game as they award it with a 8.9/10. The chaps say the gameplay is superb, it's a platform game with some RPG elements, tight controls and some amazing levels. They also praise it for its long lasting appeal, stating the game offers more than 20 hours of fun.
The graphics and sound are a bit less impressive but they still get a 7.5/10. In 2D the graphics look pretty good they say, but in 3D they don't look as pretty anymore. Overall they say this is a game that you should buy:
It's a Mario game and for some that will be enough. It's also one part platformer and another part RPG, successfully dabbling in both genres. It controls tightly and uses the Wii remote in a smart manner without stepping into forced territory. The new 2D-to-3D dynamic is built around clever and surprisingly complex puzzles that will challenge and impress you. And it all comes together to make Super Paper Mario a highly enjoyable title, whether you want to call it a platformer, an RPG, or something in-between. You will have fun and the fun will last for a good while, plain and simple.They also published a 6.5 minutes long video showing some of the gameplay: