Aesthetically and functionally the greatest handheld gaming-centric device ever built. Whereas the New 3DS XL would typically take that title, or maybe even the Switch, the New 3DS has two things that set it above the others.
1. Portability. Far greater portable shape and size than the New 3DS XL or the Switch, and even the Vita for that matter. Fits in a pocket easily, albeit with a slight bulge.
2. Aesthetic. Some folks will say the New 3DS XL special editions looks better, and in the case of the Majora's Mask edition, I would be inclined to agree but the simple off-white tone with the SNES buttons make this an immediately more attractive system. But the best part? Customization. Faceplates representing franchises like Zelda, Pokemon, Mario, etc make this a worthy investment and a lot of fun in itself. Personally I rock the Blastoise plates from the 20th Anniversary Pokemon Edition (btw greatest special edition console ever made IMO) but there are plenty of different flavors to choose from.
While the system does have it's flaws, it's completely forgiven for the things it gets right. But on the subject of flaws, they do exist.
For instance, the battery life is horrid when compared to even smaller phones processing much more than some polygons. 3D will have a noticeable effect on battery life. Best to keep a charger nearby.
Also, while it is a simple update, it was outshined graphically by the Vita a couple years prior and completely devastated by the Switch a few years later, all while being rocked by smartphones entirely. Resolution is a bit better than the New 3DS XL but that doesn't make it even remotely pleasant when playing a game like Xenoblades. Personally I find this to be its biggest flaw but I understand most won't see that as big an issue.
All in all, the updated processing power, superior games library and all around sleek, refined feel make this the best 3DS variant, and by extension handheld, ever built. I would highly recommend getting one while you still can.