You can configure your Kindle to display better readable text and more text per page while keeping your preferred font size.
Her a side-by-side comparison of the same page with different settings:
|Standard||Typeface: condensed, Line Spacing: small|
You can change these settings via the “Aa” key located on the keyboard.
The new Kindles without keyboard by default have a ghosting issue. After paging you see a slight ghost of white letters from the previous page and the characters are slightly less crisp.
The ghosting seems to be caused by an optimization making paging faster. You can get rid of it by turning “Page Refresh” on via settings.