I got to try one of these a while back and I personally have to say it's a bit generous to call them e-paper. These are more like reflective LCDs you'd see in a GameBoy. You'll notice all marketing photos of it are in either direct sunlight or have the backlight on. I compared it to my reMarkable in an indoor setting and I would honestly prefer the reMarkable's low FPS over the Daylight's low reflectivity for reading books or taking notes.
Of course this all changes if you plan to watch videos or whatever on it - but for me personally the value proposition of an e-paper tablet is not about being able to consume that kind of stuff.
In the version I tested you can adjust the backlight brightness or turn it off completely at any time, it's a bit like the reMarkable but about half as reflective (the whites are more like gray). If you turn on the backlight then it's effectively just a normal backlit tablet but with a monochrome display and night color mode.
If you're indoors without the sun shining directly at the tablet or without good lighting, in my experience you need to use the backlight for it to be usable, whereas the reMarkable is much more reflective and as easy to read as normal paper in any lighting conditions.
Of course this all changes if you plan to watch videos or whatever on it - but for me personally the value proposition of an e-paper tablet is not about being able to consume that kind of stuff.