The clock was shipped and arrived quite promptly (for international shipping); already showing correct time ;)
On the outside, I find it very stylish and minimalistic. It really stands out among the "DIY clock"-type things - it feels really "polished and finished". The functionality is as descibed, no unneeded fancy features. "Just works." The display is crisp and very readable - it is e-paper after all, like a Kindle. With a couple of button presses there is an info screen which shows battery status and uptime. The claim of battery longevity seems to hold up: I've had the clock on for 3 weeks and the charge is still 99%.
I've opened the clock (needs a small allen key), and the circuit and wiring is of good quality and good design. (It simply uses a 32768Hz quartz crystal routed to the main atmega328p MCU to keep track of time, there is no RTC.) The schematic and firmware sources are available through author's website; the standard AVR 6-pin ISP header is already soldered on the PCB. So potential firmware updating does require external hardware (AVR ISP programmer with 3.3V signals), it is pretty standard and well documented (one can also use an Arduino to do this in a pinch). The version of firmware that was shipped with my clock is pretty good and "feature complete" however, so no real need for this.
Overall, this is an awesome clock for both actual use and "avr-hacking".
I have a thing for clocks, and immediately fell for this minimalistic e-ink clock.
The 3D-printed enclosure has a nice finish, and I am really happy with the almost handwritten numbers on the clock face.
I might not have read through all the available documentation, but I am really happy that the clock is rechargeable (up to six months of battery time), I did not expect that. There are small touches everywhere that makes this feel like a premium product. Pressing buttons on the backside brings up menus, the clock will tell you when/how much it's charging or when it needs charging, and there's even a function to remove ghosting from the e-ink display.
It's a five out of five on all accounts, thanks for an excellent clock!