Microsoft dismisses 3D as "future" technology

[theRepublic]

Reasonable said:

So long as you hold your head very still...

This impression says that there is a good viewing angle.  It is only when you view it from the side that it becomes blurry.

The effect is pronounced, but seems far less distracting than you'd expect. The lack of plastic glasses imparts a level of viewing comfort that you simply don't get from 3D televisions, though the comparatively smaller screen is also easier on the eyes. The visuals are bright -- easily on par with the DS Lite -- and offer a good viewing angle. However, viewing from the side reveals the blurry, overlaying effect of the 3D screen, so you'll want to turn the 3D effect down via the slider.

http://www.joystiq.com/2010/06/15/nintendo-3ds-first-hands-on/