I don't need to tell you that an awful lot of information is shared in PDF format – and rightly so. It allows for the distribution of information across different platforms in a way that the sender can be assured that the recipient sees things just as they want them to be seen. But PDFs can be annoying to the recipient, especially if you are working on a smartphone.
If you want to annotate a PDF for your own use or for sharing with colleagues you need a separate app. If you want to fill out PDF forms you need a separate app. If you want to sign PDFs for returning to the sender, you need... well, you get the point. There are plenty of apps that offer PDF editing and annotation services; PDF Expert 5 is not one of the freebies, and it is relatively expensive. But it does have a whole lot of features and it is probably the only PDF editing app you will ever need.
For example it can be used to highlight text, fill in forms, make notes, draw onto forms, share files, use passwords and use the text-to-speech capability in iOS7 for those times when you don't want to read and would rather be read to.
Product: PDF Expert 5