I've got a 3DS XL released in 2012. I'd like to know how the "new" 3DS XL, released in 2014, is different so I can figure out if it is worth the upgrade.
The most notable changes from the 3DS XL to the New 3DS XL include:
"Super Stable 3D". A feature that makes use of the front IR camera to track your face to adapt the 3D image appropriately, which improves the 3D. Thanks to it, you won't have to worry about holding the device at the right angle as much as before.
The New 3DS XL is slightly larger than its predecessor and weighs slightly less.
Cartridge slot, stylus holder, and the power button have been moved to different locations.
The physical WiFi switch has been removed in favor of a software toggle.
The New 3DS has a faster processor and more RAM, which means some games can only run on the New one (list of exclusives). Some 3DS games benefit from the extra performance, such as better framerates (Hyrule Warriors) or faster loading times (Super Smash Bros. for 3DS). Aside from that, the improved specs greatly reduce the time it takes for the system to suspend a game.
2 new shoulder buttons (ZR & ZL) as well as a second analog stick (C stick), rendering the Circle Pad Pro accessory obsolete.
Has an NFC reader right below the lower screen.
Uses Micro-SD cards instead of regular SD cards. If you're not already using a Micro-SD card via an adapter, you'll have to buy a new SD card to increase the New 3DS' storage. Unlike with the older models, you'll have to use a screwdriver to insert/exchange SD cards in the New 3DS, due to the slot being next to the battery compartment, whose cover is secured by screws.
The AC adapter is not included in the package, so you'll need to keep your old AC adapter, or buy one separately.
One thing to keep in mind: The regular New 3DS also has colored face buttons (ABXY) which match the colors of the SNES controller, and supports replaceable faceplates. The New 3DS XL does not support faceplates, and the coloration is applied to the buttons' text instead of the buttons themselves, therefore being much less noticeable.