Sales figures can be somewhat hard to interpret on their own; what sounds impressive without context may suddenly seem far less so when seen in relation with other relevant information. It's about the big picture, and now there's an actual big picture to help put the figurative one in perspective.
The above infographic (available in its entirety here) was compiled by VentureBeat using information provided by Statista. It shows how the Vita's first week of sales compares to the those seen by the DS, 3DS and PSP in different regions, as well as globally. For some bonus relevancy, it also ranks the best-selling handheld consoles of all time.
If anything, it proves that tastes vary widely by region, and that relatively low first-week sales (see: PSP sales in Japan) don't necessarily translate to poor lifetime performance. It also reaffirms that infographics are the coolest way to display statistical data.