Readdle announced Wednesday the release of PDF Expert 6 for iPhone and iPad. The update includes a new interface, the ability to password protect files, and you can work from and save to Dropbox. On the editing side, users can edit PDF text, add and replace images, add links to text and pictures, and redact content. The company put together a good video showing off the new features (below). PDF Expert 6 is available now on the App Store at $9.99.