Zekkyou on 22 January 2015
I'd say it's probably Nintendo's least successful core handheld ever (both in sales and profitability, though if Nintendo hold off on its successor it might be able to scrape past the GBA/PSP in LT hardware), but the "least" here is relative to a very high standard set by its predecessors. The 3DS in itself has still been quite a big success.
Even with its early failings it will still have generated Nintendo a lot of profit, and has managed to maintain a significant install base despite incredibly strong competition from mobile devices. I don't think it could have done much better, all things considered.
