Here is a quick review of the GPD Win, as I played a bit with it:
As expected, the keyboard is pretty bad. The layout can be confusing, the keys are to close to each other, and the key "click" like some old joystick button. The keys are a bit hard to press (maybe to mitigate the fact that they are tightly packed with mostly no gap between each).
This is a gaming console, not really a general purpose computer...
Game controls are pretty good. A few games were installed, and I mainly played Mirror Edge (with a long session of half an hour at least). The games is quite smooth, with 30fps (then after 10min or so lowering at 20fps because of the heat, but still playable with no issue). I had a good gaming experience with Mirror Edge all in all.
Minecraft was also present, and can work with an XBox controler. But, Minecraft detect the presence of an XBox controler at start. Once started, plugin in an XBox controler will do nothing. And that's one of the main issue. When the swtich is in "Mouse mode" (like it's suppose to be when you are using Windows), the XBox controler is not pluged in. It is when you switch to "XBox mode" (you hear the little "dingdang" windows does when an USB device is connected). So, to use the integrated controls with Minecraft, you have to launch Minecraft in the XBox mode, using the keyboard or the touchscreen... That's quite counter-intuitive. Once correctly launched, it was running well.
Another point, if your game is a keyboard only game (i.e. some indie title), well, because of the keyboard, and the fact the Dpad is NOT cursors keys (or WASD), you will need to use some software like "joy2key" to be abble to play.
A last point I notices, is about the shoulders buttons. The 4 shoulders are buttons. But an XBox360 controler as 2 shoulder buttons, and 2 analog shoulders. This is used for racing games or flight/combats sims for example. No ideas how it will work a racing game...
In conclusion, it can be nice to play some (not too demanding) AAA Title (but it can be frustarting sometimes), but it will not be a nice machine for hacking (even if Linux can be installed on).