The PEZ was my first e-book reader.
My only gripe is all the models all use a 4:3 ratio display (a standard TV/computer ratio rotated portrait) and I find I break readers trance by all the page turns (with black flashes). For me, that is 2 or 3 PEZ page turns a minute. Anoying.
I measured (the printed area) one of my 1000 or so dead tree paperback books.
The text is formatted 9:16 (

Wide screen TV, rotated).
Are you listening, product designers 600x1066 (check my maths?) would allow the same width, but slightly longer display a full paperback page with very little reduction in font size and we would have the page formated.