iOS apps are, for me, a lot like cable channels: No matter how many I have on my iPad or my iPod touch, I only use a dozen or so on a regular basis. The others I don't delete because they give me some feeling of comfort, as in, "I may need this one day."

GoodReader 4 provides users with useful file management tools, like file compression and extraction.

GoodReader, which I've been using for more than four years, has been one of the few that I've never even considered deleting, because it's proven useful in so many ways. Its core functions have been, and remain, in the realms of PDF file management, viewing, and annotation.

The $7 GoodReader 4, released recently by Good.iWare, is an entirely new app in the sense that it must be paid for and downloaded from the App Store even if you've already purchased earlier versions for the iPhone or iPad. After downloading, upgraders can use GoodReader 4's built-in migration assistant to transfer files, folders, and settings from the earlier version.

Perhaps it requires a separate download because this version is a universal app, unlike its still-available predecessors. It also includes PDF file creation, extraction, merge, and editing functions not available in GoodReader for iPhone and GoodReader for iPad versions 3.21 and earlier.

This file began as a form downloaded from the web using GoodReader 4's built-in browser. It was subsequently annotated using the typewriter, drawing, and sticky note tools.

The newer version of GoodReader has, in addition to new capabilities, a slick new look and feel. Often a striking visual update accompanied by added functionality comes with a steep learning curve for long-time users, but GoodReader 4's design is clearly built upon that of earlier versions. In short, if you're upgrading, you can get right to work (or play) with the new version and learn the app's new features as you go. New users will be treated to an elegant, largely intuitive interface that deftly accommodates the app's many and complex capabilities.

While there are a number of other good PDF readers and editors for iOS, as well as robust apps for viewing videos and listening to audio files, GoodReader for iPhone and GoodReader for iPad have long stood out for doing all of these things well, and GoodReader 4 is a clear improvement from earlier versions.

GoodReader 4 builds on the earlier versions' already excellent file and folder management tools. Users can import PDF files from Mobile Safari using the "Open In..." extension (known technically as iOS’s inter-app Document Interchange), and you can also import Web pages and PDFs using GoodReader 4’s built-in (but bare-bones) browser. That said, the app works most smoothly when used in conjunction with Dropbox, Google Drive, box.net, iCloud, and other cloud storage services. You can set up GoodReader to download, upload, and automatically sync files and folders to these services; the app also supports downloading attachments from email accounts.

This version is a universal app, and provides the same robust PDF editing tools on the iPhone and iPad. The ability view documents at 50 times their original size makes using the app's tools on a small screen a breeze.

The newer app, like the original, enables you to mark up and annotate PDF documents in many ways: You can draw using ovals, rectangles, straight-lines, arrows, and freehand tools in any color and thickness, highlight text and images, and insert text boxes and pop-up sticky notes. (When you begin to annotate a file, the app automatically prompts you with an option to create a copy of the document for notation purposes, a very useful reminder that it is often a good idea to keep an untouched original. A very nifty feature is the ability to view, save, and email only your annotations.)

Besides the new look, the upgrade includes a slew of new PDF page management tools, including the ability to easily add, delete, and rearrange a document's pages. You can also now extract pages as new files, email individual pages, split documents, and append pages from other documents. Long documents are now much easier to notate and navigate thanks to a faster PDF rendering engine and a thumbnail page viewer. You can also now create new blank PDF files from within GoodReader.

Bottom line

GoodReader 4 now coexists with the separate versions of GoodReader 3 for the iPhone and iPad, and seeing as these separate apps cost $5 each, the $7 universal version is a bargain for most new users. If you currently use GoodReader 3.21 or earlier, the upgrade is probably worthwhile simply for its revamped look and speedier PDF viewing and navigation capabilities.