My brother got one on launch day, he's a big Nintendo fanboy and buys all their systems and most of the first-party games. I've tried the system a few times, the 3D isn't exactly what I expected though. Like others have mentioned, it doesn't even look good unless you have it in that "sweet spot" but once it is there it really does look 3D. But even with it being 3D, it doesn't actually pop out at you. When they say "3D" they mean it adds depth and you see into the 3D world, it's definitely something that's easier to see then explain.
I personally wouldn't buy one, and even less so with the launch titles out right now.
The innovation behind it is great, I mean in the future I imagine lots of, if not all, handheld devices will be 3D, but just not in the ways we might see 3D right now.
Nintendo really is revolutionary in the devices they make, they have the right concepts for new technologies, though sometimes their delivery is a bit off for my tastes.