Previous Kaleido products are fundamentally flawed. I'd hoped they would bin it for something better rather than make incremental improvements. Think it's also debatable what value colour brings unless you are regularly reading full colour magazines, PDFs etc.
A photo frame in your home that rotates through a set of photos. My grandmother had one to help her remember her family, but it was an LCD. A color e-ink one would be so much nicer.
Any sort of information panel/dashboard or even just graphs inside education books. There are e-ink screens with only a couple colors (like black, white, red, and yellow), which lets you do things like "make this graph red when my waterheater is broken" but a full-color display opens up the possibilities considerably! For example, having line graphs with multiple lines.
If it was high refresh rate, I would consider it for a computer display for coding. I could never give up syntax highlighting so I need color.
The e-ink photo frames that do this pretty much all use spectra panels instead of kaleido panels. Kaleido is a grayscale eink panel with a color filter array on top, spectra uses eink cells with up to six different pigments.
Spectra ends up being much brighter/clearer and with much better color fidelity (like nice magazine print vs color newspaper), but the downside is that it can take like 30 seconds to properly refresh the panel. That's unacceptable for a tablet, but fine for a photo frame.
A colleague has the colour version of the same tablet, with a Kaleido 3 screen. It's terrible. It's unusable indoors without the backlight.
That's not great for battery life.
> That's not great for battery life.
Yes, I would really love this as well. They make tri- and quad-color e-ink displays, but I've only ever seen the 'badge' size. I'd buy a full sized reader with just that right now.
Obviously ereaders are appliance-like in part because e-ink screens have bad color and update rates, but at least they'd be practical outside in direct sunlight, and it's not like ereaders would suddenly become technically impossible to be appliance-like.
There's no question that there's room for improvement! But if you're only reading prose or black & white documents, you'd be better served by a black & white screen. Which is not cause to say that a useful, functional technology is "fundamentally flawed".