On any reading page, I notice that some "I"s are thinner and darker than others, and some vertical lines of an alphabet (eg the vertical stroke of "h") appear to be thinner and darker than the rest.

Also some letters appear to be lighter than others, giving the appearance of being out of focus.

Does anyone have the same issue?
I do not have that issue on my iriver Story. Do you get this problem for all the books you view or just one specific book? Have you tried different types (PDF, EPUB or TXT) to see if you get the issue with all formats? Do you get the same problem if you change the size with the magnifying glass on the keyboard?

In the new firmware (v1.61) they have added support for dithering. You can try to turn that off or on and see if you get any difference.
It's more obvious with epubs, but less obvious with pdfs. I could see that problem even when I increased the font size. But if I don't look closely at individual letters, it's fine.