They're "okay".
The surface finish reminds me of SP DCS/DSA/DSS. Almost like fine grained sandpaper; not unpleasant, but not much like GMK.
The looks are okay, from far away it's mostly like GMK. On closer inspection, you don't have weird kerning issues like JTK. But you do have the same "InSert" problem as JTK. The alpha legends also have inconsistent thickness, notably the "Q". And the modifier font just isn't as nice.
The scoops in the keycaps are also slightly deeper. I confirmed this by measuring with calipers, although I don't remember the numbers offhand.
The keycap walls are thinner, and the sound is more "plinky" and "glassy" than GMK. It reminds me, again, of SP DSA/DCS/DSS.
Overall I'd say these are okay, I guess. I'd rather have JTK, and it's kind of a hard sell when GMK WoB isn't that much more expensive on Drop. And given that they already sound like DCS and have the same surface finish, I might prefer DCS over these, which at least has a somewhat unusual contour.
If you don't mind blanks, the Keyreative ABS blanks are much better quality. Not to mention 1/3 of the price.