So after spending a few hours with the New 3DS XL I can say a few things.
1 - The C-Stick is nice but they need to add a sensitivity adjuster. It also takes a bit to get used to.
2 - Your old XL grips and things will not fit this. It's too wide. Your hands can start to hurt after a bit due to the console being too thin. Currently only been able to find 1 grip for it only available in Japan and its sold out =/
3 - It's very nice and the buttons feel better then on the older 3DS systems.
4 - *** Micro SD cards >_>
5 - They System transfer takes a LONG time w/o a PC transfer. Even picking the Save data only transfer took over an hour.
6 - The Face tracking for 3D is VASTLY improved. So Much so you may want to go back and try old games with it on for the first time.
Overall: 7.5/10
While an overall improvement in both form and function the systems clunky initial set up, weird C-stick being a mouse nub, and the change from normal SD to Micro, make it a far from perfect transition.
TL;DL : Wait a bit if you have big hands for grips to come out and when you do buy it, buy a Micro SD card of your own.