PDF Max is a complete PDF viewer that provides you with multiple tools for annotating, editing, and reviewing PDF documents. Download documents to the app from multiple sources including Dropbox, Google Drive, SkyDrive, and Box, and then view, edit, or share them through a variety of other programs.
The interface of PDF Max is accessible and intuitive, with options for viewing documents organized by name or date. Adding a new document is straightforward, as you can just tap the "+" icon in the upper left-hand corner to begin. Next, select the source of the document, or create a new folder to help sort existing documents. Once you've downloaded your chosen PDF, just tap it to open and start reading or editing. Documents scroll smoothly up and down, and tabs on either side of the screen provide access to the various editing and note-taking tools available. You can also highlight, underline, copy, and more by holding your finger down on an area of text and selecting your desired action from the menu that pops up.
This app is free to download and use, although there are quite a few advanced features that are only available through in-app purchases. These include the Essentials Package for $4.99, the Form Filling Package for $3.99, and the Standard Annotating Package for $0.99. Overall, this app works well and has a nice set of features, even in the free version. If you're looking for a fully-functional PDF editing program, you'll definitely have to pay for some of the available packages or upgrade to the Pro version. But for as well as it works, this app is worth the money.