There are some major changes in this release. I should name the version 22.
Euler now exports in a more friendly style. The paragraphs are now HTML paragraphs, not preformatted. The output no longer has a gray background. The colors are a bit darker. By default, Latex formulas link to the larger images, even if that does not look so good in IE or Firefox. Other images link to the image with the actual size.
The notebook got a spell checker for English. You can add a list of words in your language, if you have one. Or you can add all unknown words from a notebook.
Many pages of the documentation, the tutorials and the examples have been rewritten.