When the DS came out it was clearly rushed. I mean the only first party launch title was a port of an N64 game! Come on! I figured it would bite them in the ass.
It didn't and this won't either. It's clear that for a product like this there is always a group of early adopters that will carry it for the first little while. Eventually things have to shape up to get everyone else on board, but you really don't need a strong launch.
Or at least you don't if you already have a strong brand people are interested in. I think a newcomer or a follow-up to a less successful product needs a stronger launch. The PSP2 will need a strong launch. The Gamecube is an example of a console that needed to make a much stronger first impression than it did.
Everyone loves the GBA and thus wants to love to the DS. The DS gets away with blatantly coasting for the first little while. The N64 is not particularly popular so people need to be given a reason to care about or even notice the Gamecube. The Cube makes a weak first impression, fails to win the doubters over, and never really goes anywhere.
Of course the key is that you do deliver in time. The N64 started out okay with a really awesome killer app at launch but it failed to maintain any momentum.