It works exactly as described. This is one of those extensions you don't realize you need until you see the end results.

Update, Issue: It does not work well with 'Refined Hacker News' (RHN). Because the purpose of this extension is to reduce the width of paragraphs, it also reduced the width on RHN's _inline_ commenting box (when replying to a comment). It created scrolling problems, forcing me to disable this extension.

This is not Readable's fault. It does exactly what it's suppose to do. There's just a conflict between two extensions.