This is my first GMK set, and I can definitely feel the quality on these. They're thick, they have a unique sound profile that's a bit deeper than other doubleshot caps (although I've only tried doubleshot PBT), and they only shine a little bit around WASD after a month of use.
The colour is NOT what I expected. That's not to say they look bad, necessarily, but they definitely don't look exactly like the keycaps I purchased. Renders for these caps made them look more grey and slightly muted, but the keycaps that shipped turned out more blue and are more colourful than I expected. (This is the same on GMK Bushido, which it is based on.) I don't hate the colour - but I definitely would be enjoying this set more had it been the grey colour I expected. Apparently the grey comes out more in specific lighting. I haven't been able to see that.
As of right now I have them on a black Idobao ID80, but I'm definitely going to be taking them off soon and throwing them on a different board. This colour doesn't look great on black, in my opinion. Give it a bit more colour. (Or don't. You do you. I'm not your mother.)
Not a bad purchase at all if you're looking for new keycaps - but look at some product photos first, not just the renders.