"Many people with cognitive disabilities have a great deal of trouble with blocks of text that are justified (aligned to both the left and the right margins). The spaces between words create "rivers of white" running down the page, which can make the text difficult for some people to read. This failure describes situations where this confusing text layout occurs. The best way to avoid this problem is not to create text layout that is fully justified (aligned to both the left and the right margins)."
You shouldn't turn on justification without also turning on hyphenation.
If you add 'hyphens: auto' and '-moz-hyphens: auto' then it looks much better on Firefox. Chrome doesn't support hyphenation though...
Interesting, though the readability problem from the original text has much to do with trying to justify text in a very small column, which means excessive spacing has to be used.
"Many people with cognitive disabilities have a great deal of trouble with blocks of text that are justified (aligned to both the left and the right margins). The spaces between words create "rivers of white" running down the page, which can make the text difficult for some people to read. This failure describes situations where this confusing text layout occurs. The best way to avoid this problem is not to create text layout that is fully justified (aligned to both the left and the right margins)."
[0] http://www.w3.org/TR/WCAG20-TECHS/F88.html