THE SHORT ANSWER
E-Ink is a convincing sketchbook, not a complete art studio.
E-Ink tablets are good for drawing when the job is to catch an idea, build clean line art or make a thoughtful monochrome study. The reflective screen stays readable in bright ambient light, the stylus can respond to pressure and tilt, and the limited interface can help you stay with the page.
The limits arrive when you need accurate color, many layers, fast transformations, large brushes or specialist apps. Current color E-Ink can add useful hues, but it still shows a smaller, softer-looking palette than a modern LCD or OLED tablet. Buy one for the paper-like workflow, not because it has replaced Photoshop, Procreate or a pen display.