Very good, but don't expect today's level of 3D wow power. Awesome platform game.
Some comments I have seen such as "The nintendo is dead. Deal with it." are totally missing the point of the whole game. As a whole, the game is AMAZING. Great level design. Tight controls and the ability to make you think quickly. Before people go dissing the game, it needs to be criticized for what it is and not what it isn't. It is a great platform game. It is a creative take on a 2D platformer. It is NOT a highly graphic laden 3D shooter, nor an intricate plot-based RPG.
Taken for what it is, the game is great.