Within the past two years, the Adobe Acrobat suite of programs and their Portable Document Format (PDF) have become the de facto standard for cross-platform, electronic document management and distribution. Much of this widespread popularity can be attributed to the Internet and the overall ease in which PDF files can be uploaded, linked to, and viewed virtually anywhere regardless of system. Capitalizing on this success, Adobe Acrobat 4.0 brings a solid update to an already solid standard.
Adobe Acrobat is actually a suite of programs and utilities. Acrobat (formerly Acrobat Exchange) is used to create, edit, modify, and merge PDF files. Acrobat Distiller converts postscript files to PDF, while the PDF Writer printer icon converts most other types of files to PDF. Acrobat Catalog is an indispensable utility for generating full-text, searchable indexes of multiple PDF files. Acrobat Reader and the PDF Viewer web browser plug-in are read-only, freeware components, and can be used to view PDF files online or off.
Several handy features have been added to Acrobat, including small thumbnails, highlighting, annotations, context-specific optimization, and batch processing for multiple documents. One utterly minor yet much appreciated feature is the new, "front forward" bookmark system. Previously, when working with a combination of long bookmarks and small screen real estate, much of the bookmarks text would be hidden behind the document pane. Now, when rolling the cursor over each bookmark, the partially hidden text brings itself forward -- complete with a different background color to make the text even more easy to read. The small thumbnails are also a nice touch, particularly when navigating through long documents, or when working on a small screen.
Adobe has revamped Acrobat's interface by adding several new buttons to the tool bar and then splitting it up so one half occupies the left vertical while the other fills the top horizontal. One questionable interface change in Acrobat 4.0 is the new "Show/Hide Navigation Pane" button in place of the three previous buttons for bookmarks, thumbnails, and document-only views. When clicking the Show/Hide button, a tabbed pane appears on the left-hand side with options for the three previously mentioned views. This change isn't really bad, and is actually pretty intuitive once you get used to it, but Adobe has opted to place all the menu commands for each of these views in a tiny window accessed by an even tinier triangle next to each tab. Since many of these commands like "Create All ThumbNails" and "Add Bookmark" were previously accessible via obvious pull-down menus, relocating them to this obscure little triangle can be quite confusing for any seasoned Acrobat user. Fortunately, keyboard commands for these commonly-accessed tasks still work.
Mac inequality
For reasons known only to Adobe, the Mac version of Acrobat 4.0 lacks certain new features available in the Windows version. Much has already been written about this, including some half-hearted explanations from Adobe management about how Mac Acrobat users tend to have different needs than Windows Acrobat users, which in turn resulted in slightly different features on the Mac and Windows versions of the product. This explanation / rationalization may have been more credible if there were some Mac-only features to Acrobat (beyond the typical ease-of-use features standard to Macs like drag and drop, for example). However, the "different features" can be summed up as this: the Windows version has them, and the Mac version doesn't.
Two of these Windows-only features are Web Capture and SelfSign (a digital signature). Web Capture apparently allows entire directories to be converted into PDFs, along with all corresponding links, all bookmarked and merged together into one handy file. The SelfSign / digital signature feature also shows promise, assuming Adobe ever gets around to releasing it for the Mac. With it, users can have multiple reviewers of documents sign-off electronically.
In spite of the Windows-only features, the pros of Acrobat 4.0 generally outweigh the cons. The interface changes are for the most part well thought-out, though moving some commonly-used commands from pull-down menus to cryptic, tiny, menus on the tool bar is a little odd. Acrobat Catalog is a particularly helpful, unsung hero, as is the PDF Viewer web browser plug-in. Overall, Adobe has released a solid, stable upgrade to an invaluable suite of products. 
