Light Editing Tools
The most commonly requested PDF Apps are the ones used for light document editing. My research reveals at least three tools which can be used to mark up existing PDF files: ezPDFReader Pro (Android), iAnnotate PDF (iOS only), and GoodReader (iOS only). The files can be marked with highlighting, lines, stars, pop-up comments, and some even include the ability to insert shapes and text boxes.
Although these tools will not replace the need for Adobe Acrobat on a personal computer, they bring some basic capabilities to mobile devices. The features of each of these apps vary significantly, and are frequently updated, so users should test the capabilities of each app thoroughly before deploying them in a production situation.
The market for mobile PDF apps is changing rapidly, and although there is not a single solution which incorporates all of the functions needed by mobile professionals. A number of inexpensive solutions are available which perform basic tasks, and users who need more capabilities may need to use Adobe Acrobat on a personal computer until apps are available which emulate these capabilities on common mobile platforms.