The 3DS sold more units than any other handheld console ever has at launch. Regardless of that, though, the 3DS isn't exactly selling incredibly. The people that didn't get caught up in the hype aren't buying into it quite yet, either. The 3DS didn't have a good selection of launch titles, and the titles are slowly trickling in now. I think with the eShop here it will probably catch the interest of people a lot more. As newer and better games come to the system it will attract a wider audience, too. The 3DS hit stores nice and hard at the beginning, but flopped over right away. I'm sure Nintendo will be able to dig it back up... they don't want a failure as bad as the Gamecube again. I loved the Gamecube... but was an extreme marketing failure for Nintendo. It didn't sell at all.
i just haven't bought it yet because i don't have the money. I imagine that could be why others have not bought it as well. I know i will sound like a broken record when i say this because everyone else has already said it but just give it time, it will be a hit in time.