The Sky3DS is a ticking time bomb. It will become useless the moment Nintendo releases an update that blocks it. Unlike Gateway, there is no way to update the cartridge once an update blocks it and it can't run homebrew (well it can via Cubic Ninja exploit, but not if your on firmware 9.3 or above!) or make use of Emunand or firmware spoofing. Hell it can't even undo region lock.
The moment it gets blocked (And I predict this will happen soon. Perhaps with the first major firmware update like v10.0) You're stuck with a $100 piece of plastic. You can just never update, but you lose out on a LOT of future games if you do this.
I feel sorry for all the poor sheep that will fall victim to Sky3DS.