It is definitely not doing great and most likely is overtracked in EMEAA, as well. And while it is still doing very well in Japan, we need to wait til Sony launches the Vita to see how it will affect sales.
But still, it's way to early to call it a failure. As above, we need to see what affect the Vita's launch has on the 3DS's sales in Japan. And when it can truly be predicted is late holiday next year, when we see what kind of impact the Vita has on it WW.