Got mine yesterday and have spent hours playing with it. I definitely love it! There are some ups and downs, so I figured I'd put my thoughts into writing.
Hardware
Pros: Feels solid. Opens with one hand much easier than the DS lite. Placement of cameras prevents obstructions and inner camera is at better angle than DSi.
Cons: Though it has a great design, the glossiness of the unit attracts fingerprints way too much. The hinge is a little loose, too. Also, 3D effect only works in certain ranges, so be careful how you move. Also, the battery life is sub-par. You only get 3-5 hours of game play in 3DS mode. DS mode lasts longer, but nowhere