I have the GKD pixel 1 and the build quality is insanely good; the screen is excellent and the sound is surprisingly amazing. The only downside is the stock firmware which is an opendingux type of stuff, it kind of sucks and regarding emulation power it lacks a bit of power; tekken 3 runs on it, but slightly slower than it should, you won't even notice it unless you are used to play that game on a faster device. It's not annoying, in fact it adds pace to the gameplay, but that shows the hardware limitations. Also, the console is slightly smaller than this one.
I really ponder if I should buy the new model, but for anyone wondering if that console is worth its price, it definitely is, you won't regret to own one, it's a master piece in its own category.
Back in the day (around 1995) you had the Nintendo Gameboy (DMG) (good but colorless), the Sega gamegear (good also, but with colors but it's not a gameboy...), and the Atari Lynx (which looked nice but sucked, hard). And at the extreme end of the spectrum, you also had the PC Engine GT, and that handheld stood apart from the rest, it was a UFO, literally Batman's handheld
Well, the GKD pixel is that sort of handheld, it's the special one, it's the obscure-little-known one that delivers