There were lots and lots of problems with the Cosmo as a phone, build quality first and foremost, but I'll focus on the screen/keyboard combo since that's the point of comparison with the GPD.
First, the keyboard: The Cosmo keyboard is not designed for thumb typing. You can do it, but it's a bit awkward. The phone is not comfortable to hold in this configuration - it's thin, wide, top heavy, and the hinge has sharp edges. The generous key travel also works against you when thumb typing. It seems that you are basically always meant to put the phone on a flat surface and touch-type - but it's not very good at that either. It has no feet on the (slightly curved!) bottom surface, and while the rear hinge is meant to act as a kind of kickstand, the design means that force of typing transfers to the screen, causing it to wobble with every keystroke. The keys themselves are as nice as is possible in that size, but touch-typing at a table while on the go is a very narrow use case. The device feels delicate and fragile. Also - while this isn't a completely fair comparison as I've only had the GPD for two months - after a year the keyboard began missing keystrokes (and this was a replacement keyboard, since the one it came with did that from day 1).
Next the screen - a super-high aspect ratio smartphone screen turned landscape is actually really annoying. You have almost no vertical real estate, whereas most phone apps assume that the vertical axis is where all the real estate is and consequently put menu bars at the top and the bottom, eroding it further. There's very little gap between the touchscreen and the keyboard, so accidental touches are common. Switching between touchscreen and keyboard interaction is even more annoying that switching between mouse and keyboard on a desktop, either because you have to transfer the weight of the device to one hand if you're holding it, or if it's on a table because you must gently prod at the screen without tipping the thing over, or brace the screen from behind. Also the screen only opens to one very wide angle (cheerfully described by Planet as "the optimum angle"). There's volume buttons, but they're awkwardly on the back of the screen, which would make sense if they worked when the device is closed, which they DON'T.
Now, the GPD Micro PC: no touchscreen, which is actually great because all interactions that change the state of the device require definite action and make a physical "click" - you don't have to worry about accidentally brushing it the wrong way. This actually takes a lot of cognitive load off. It's comfortable to hold in two hands for thumb typing (but also has rubber feet so you can set it down). The touchpad is accessible with a fractional movement of the thumb, so switching time is minimized. There's dedicated and easily accessible volume buttons. The screen has a comfortable aspect ratio and can be set to any angle, where it remains stiffly. And most importantly, it runs desktop software. With these controls, it's more ergonomic to use desktop software in miniature than it is to poke about at a touchscreen.
Thanks indeed for the review! I came across these devices once, and I always wondered if it was more gadget-like, or really useful. Have you tried running Ubuntu MATE on it?
I was never brave enough to tinker with GNU/Linux on the Cosmo while it was my daily driver. I'm pretty sure that using the device that way comes with some pretty sever compromises.
On the Micro PC, I run Void Linux with KDE Plasma. I didn't do anything special, everything's mainline, so I'm sure at a technical level Ubuntu MATE would work perfectly well. The only interface tweaks I've made are to set the task manager to "icons only" to save space and added thermal/RAM/CPU monitors in the taskbar.
As for "toy gadget" vs "useful tool", I'd say that if you're the kind of person who likes to take your laptop everywhere, it's definitely for you.
Thanks. I meant on the Micro PC. I guess you already mentioned KDE Plasma somewhere. I definitely don't take my laptop everywhere, but I'm contemplating. Such a Micro PC looks very promising, exactly for the reasons you stated!
