The new functionality added to iText in the iText 5.4.x versions has been very popular. Thanks to this popularity, we have received a good number of bug reports. We have fixed a number of accessibility issues and we have fixed a couple of problems with the new PdfCopy features.
You will also want to check out the new features that were added to iText RUPS. It is now possible to tweak a PDF by changing entries in dictionaries. In future versions, we will add some more functionality that allows you to update an existing PDF.