I consider the lack of an sd card slot a bigger mistake/issue than the non replaceable battery. Hope they can still manage to squeeze one in.
I have suspected that phone manufacturers removed the microSD slots for a while as they tried very hard to push people into using their branded cloud storage (to be monetized through mining user's data and eventual fees) instead. That plan seems to have only worked well for a single company that sells fruit to sheep. Their competitors have gone back to including local storage options - with quite ingenious little drawers through the edges of the phones.
With this GPD Pocket, though... as far as I can tell they don't have an in-house branded cloud storage solution to try to monetize. So, if they don't have an enhanced revenue scenario (cloud storage), then it would make more sense to include the features people want. In a device of this size, my expectations isn't simply a single microSD slot. I would expect two or more slots with at least one being a full sized SD card slot - preferably with the U3 additional pins interface.
The bad stuff:
No removable battery.
No expandable on-board storage.
No 4G hardware.
Very wide - it's a long brick for a pocket.
How well will they do their Linux drivers?
The good stuff:
Relatively thin.
More screen.
X86 (a plus to me)
Linux if the drivers are good.
Tolerable keyboard (was a major reason I didn't buy a Win).
Frankly, if ED can firmly state that I'll be getting my Pyra Prototype before the end of March, I wouldn't give the GPD Pocket another glance. But, I do like my gadgets. As time drags on for the Pyra I have to give these new options consideration. I'm still on the fence on whether to get in on the pre-order for it. It isn't perfect, but it could fill a niche.