It's just a souped up 3DS with better 3D, more RAM+ CPU power, and adds a c-stick, zl and zr buttons, an upgraded camera, built in nfc amiibo support, and wireless data transfer. There's only been one game released specifically for the system, which is Xenoblade Chronicles 3D, and a few games are programmed to run better on the New Nintendo 3DS.
Right now, its in the same situation as the Nintendo DSi where it has some nice improvements overall, but most games are not going to need an upgrade to the new 3ds in order to be playable. Your regular 3DS/3DS XL should still be fine for usage for the next few years.