The main thing to look out for would still be the hardware sales numbers, the software sales for Vita seem to paint an incomplete picture of how the Vita performed (assuming that VGC doesn't take note of digital sales).
But looking at the fact that the 3DS (at least for the software) is still as thriving as ever, I don't think all of these show that the Vita's having a really good time in Japan now.
Really came as a surprise to me.







