I've used a few Gyeon products on the recommendation of the blokes who did the ceramic coating on my newer Genesis. And I've been quite impressed, but then everything is going to look good and work well on a freshly ceramic-coated car.
But my daughter's 2015 Genesis - well, that's a different story. It spent a year outside (often parked under a sappy tree)
and had not the slightest bit of any protective product left on it. After dealing with a half-dozen droplets of sap, I gave the car a thorough wash. The application of the wet coat to the entire car then took all of 7 minutes.
So, the manufacturer says just spray it onto a wet, freshly-washed car and immediately hose it off. A couple reviews I watched recommended using microfiber sponge to evenly spread the sprayed-on product before thoroughly rinsing it off. That's the way I went. Just like in the videos, the difference in water beading / sheeting was IMMEDIATELY apparent in the area where the product had been applied as compared with adjacent panels. Once the whole car was dried off, the finish was super-glossy (even on a white car), super-slick, and very even. Manufacturer claims up to 12 weeks of hydrophobic protection, but most reviewers say 4 to 8 weeks. Even at the low end, doing this once per month would involve close to zero effort.
I came away hugely impressed.
Random web product pic:
The car:
