For me the "3D gaming" concept is mostly fluff. It's not gonna be any different from "2D gaming" (I guess that's how people are calling it now... remember when Mario 64 was "3D gaming"? yeah...), except you'll have a slightly better sense of depth. It's nifty, but it's not needed.
I'm getting for the 3DS not because of the 3D effect, or even because of the stronger hardware, but because, well, it's a Nintendo handheld and those are always good... and Star Fox 64 is coming out on it, I just can't say no to that.
One of my friends actually tried the 3DS last year at E3 (lucky bastard) and he told me that the effect is actually really good. And currently there's some Best Buy stores in the US that have demo units, and the feedback I've read from those is very positive.