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.