Saw some streamed presentations of it on gamespot.com... very neat handheld... only bad thing compared to sony is that the dual screens are too seperated from each other, i'd rather have 1 wide screen.
But the cool feature is to be touchscreen and built in communicator for 100yrds.
I think the games going to be offered wil judge who's the winner.
So far, sony showed cooler games than the DS, but downside is they use CD (motor driven) as a medium rather than a hardware memory.