I have their 13in grayscale e-ink device. I assume the underlying tech is similar. What they carefully filter out is the significant ghosting of the device that builds up immediately and needs to be cleared with a button on the monitor. The contrast is also poor and blends with ghosted content so you need more time to tell what’s real or junk pixels. The front light on the device is still required in most lighting situations unless you are in sunlight. Glare from non overhead lighting is very bad and worsened by the lack of a backlight. Content on significant portions of the page will flicker as you move your mouse and corrupt content already displayed unless you press the clear button. Content will flicker on many settings even without any movement. Even on the lowest refresh rate the device is still not really usable. I originally bought this to help with eye strain, but the poor visibility of content, flickering, and clearing action make it substantially worse than a regular monitor.

Edit: I’d also add that the device emits a coil whine when the display is updating like when moving mouse. Its audible enough to hear over my wall AC unit.