To be brutally honest, it isn't portable and it isn't pretty. Yes, it's cheaper than the 3DS, and perhaps it sustains a longer battery life, but it's mono for Pete's sake, plus there are 3DS games out there where the 3D feature is somewhat necessary (Super Mario 3D Land, for example). The fact that it can only play some DS games is a bit suspicious...
My verdict is that it's just so ugly, I'd never want to buy it in a million years, even if my 3DS became broken beyond repair. Also, ever notice how the Game Boy Micro and the Wii Mini were commercial flops? Yeah, funny that.
Also, I like my hinges. The lack of a hinge makes me sad. It also earns the title of "Non-3D 3DSlab".