Finished all four regional phenomena; the Gerudo one was the best, though all of them were at least good.
The Lightning Temple in particular was super cool, they got a lot of creative mileage out of the light and mirrors mechanic, and it was clever without ever being obtuse or cryptic.
Managed to do the whole area without shelling out for desert gear, which was a fun challenge.
It's crazy, even after doing all four and playing over 40 hours, I still feel like I've barely scratched the surface of the game as a whole.