Can't wait to try out the Nintendo 3DS? Check your local Best Buy. Many (most?) of the them already have the demo kiosks up and running, and are eager to take your pre-order money.
Yesterday I had the chance to check it out for myself, and found the 3D effect to be near-perfect. The sweet spot (holding it dead center) produces no image ghosting, and the results are as good as the auto-stereoscopic screen on the Fuji W3 (pretty darn good).
The sweet spot could be wider, but unless you plan to shake your head back and forth while playing, it's not much of an issue (and will no doubt be improved in future versions of the system).
The depth slider makes it easy to tailor the effect to each game, and I found that setting the slider to halfway provides a pleasing depth effect without any eye strain.
I'm eager to see how it does with movies and photos, but the demo unit was locked into Pilotwings. There are reports that you can disable this mode, but I was approached by a sales rep before I could try.
Verdict? At $250 plus $40 per game(!), my primary use for it would probably be as a portable, glasses-free photo viewer - and my Fuji W3 alreadly serves that purpose well and puts the "cameras" on the 3DS to shame. As an iPhone game developer, it's also hard to ignore the growing number of quality Stereo-3D games on the App Store. In addition to my own experiments, there are some great 3D games like Fly Effect, Ground Effect and Crash Course (all recommended and available for $2 each). Yes, you have to wear glasses, but the effect is very similar at a fraction of the cost, and on a device you probably already own.
Still, Mario in full-color-glasses-free-3D is a pretty cool idea. A large catalog of downloadable retro games, redone in 3D and priced accordingly would make it hard to resist.