I've upgraded from the original model and honestly if you already have anything newer than that - you probably shouldn't upgrade. This is still the same Nintendo console with no technological upgrades other than the OLED. Same performance as the original, same horrible performance within Nintendo eShop.
That said, the OLED screen is absolutely beautiful. The whole console simply feels 10x more premium with the new huge display. The stand is so much better. The dock now comes with built-in Ethernet port and looks a bit more modern.
And the Splatoon 3 Edition-themed controllers (and the back of the console + front of the dock graphics) are absolutely beautiful too.
Transitioning from old to new console was okay-ish... Had to re-download everything manually from the store :/