I have a Onyx Boox Nova C that has pretty much the same technology (Kaleido Plus) and would say that the color display is mostly just a neat gimmick that comes with some tradeoffs. Compared to a pure monochrome E-Ink display the contrast is much worse and colors don’t really pop either. You basically always need at least a bit off background lighting to be able to read.
I’d recommend these types of display only if being able to read without background lighting isn’t a must and even then only for stuff that’s better with color, like notes, technical books or the occasional colored page in a book/manga. If you want to read something reliant on stunning colorful artwork like graphic novels I’d stay away.