Zelda and other Ninty exclusives, decent third party support and some HW features that users consider useful and desirable enough to justify the price.
Plus being a very well-thought-out project after a disaster on home consoles and a portable below expectations, basically it's what both Ninty fans and simple gamers that aren't Ninty haters expected from Ninty.
I'm not a Ninty fan, and I still find NS expensive for my tastes and my wallet, but I can tell an excellent product when I see it.