On December 2, 2004, the Nintendo DS went on sale in Japan. The 3DS went on sale in February 26. The consoles are different, but in many ways, similar. So which one did better out of the gate?
The Nintendo 3DS sold 374,764 units in its first week on sale. Since the portable was released on a Saturday, that means its first week was only two days long (Saturday and Sunday). The 3DS had a software attachment rate of somewhere between 0.88 and 0.95, meaning that many 3DS consoles were sold without games. This could be because the 3DS already comes with interesting on-board games, thus players didn't feel compelled to get 3DS titles.
The Nintendo DS launched on a Thursday, giving it two more days on sale. It sold 469,000 units of hardware. The DS had an attachment rate of 1.04, slightly higher than the DS. Two Nintendo DS games Super Mario 64 and Made in Wario sold around 150,000 copies each. While the biggest selling 3DS games, Professor Layton and the Miracle Mask and Nintendogs + Cats: Shiba, did not. Layton sold 119,000 copies, while the Shiba version of Nintendogs + Cats sold 68,000. There isn't yet public data on what the other two games sold.
The DS, however, wouldn't truly hit its stride until a few years after launch. Does the same fate await the 3DS?
Let's Explore 3DS Software Sales [andriasang]