Nintendo DSi doing better than expected (by me anyway)

I remember being at the Euro launch of the DS in 2005 – a slightly less slick than they are now Girls Aloud were the highlight of the Paris event - and wondering how on earth Nintendo expected their clunky and plasticky new handheld could compete with Sony's sexy PSP. I was wrong, obviously, but then the DS looks and feels a lot better now then it did then. But clearly I didn't learn. The DSi seemed to me to be nothing more than a minor upgrade but the camera-enhanced DS has shifted over 500,000 units in its first month of sale in Japan. This is practically the same as the orginal DS shifted in the same time period. Impressive stuff then, but I still don't see why the average DS owner would rush out and buy this "upgrade". Am I missing something? Are you planning on getting a DSi – or happy with your DS (or PSP)