The "New Nintendo 3DS" was released in Japan on October 11, 2014.
Three new buttons have been added: a direction stick on the right side and two new triggers. Additionally, the 3D has been improved with a wider viewing angle, and the lower screen now reads Amiibo codes. Finally, the body plates on the regular (non-LL) size body are replaceable with "cover plates", and the machine now accepts micro-SD cards only. The New 3DS is region locked and does not have an English language option. Also of note, Japanese 3DS systems do not include a charger.
I preordered a white-body version from Yodobashi Camera in Kichijōji, along with Monster Hunter cover plates. I decided to take some pictures of the unboxing to share below.
My own impressions: I find that the new 3D is noticeably better, being viewable from almost any angle. However, it does seem to flicker occasionally, just for an instant, which is quite annoying. That said, I still prefer it to my older 3DS. Also, some of the sliders and ports have been moved around to make room for the removable covers, and I much prefer their new placement. I had a tendency to accidentally adjust the volume slider while playing my old 3DS, which is no longer an issue with the new model.
You'll find my unboxing pictures below. As always, clicking an image will bring up a larger version; the remainder can be viewed without leaving this "slideshow mode" by clicking the right side of the current image.