My day job requires me to spend a great deal of time working with PDF documents. For a long time, that meant I needed to have a license for Adobe Acrobat on all of my computers. This is no small task on the Mac platform since Adobe only sells Adobe Acrobat professional for the Mac which will cost you $450. Fortunately, there are other options. Apple's own Preview application does a pretty good job of displaying PDF documents and allowing basic editing. For some people, this will be plenty. If you need something more robust however, Smile On My Mac's PDFPen may be just what you're looking for.
The tools in PDFPen are much more robust than those offered in Preview. Accessing a PDF document with PDFPen, you can add text, images, and signatures. You can also highlight a text field and open it as an editable text block. So when you receive a PDF document within mistake or typos, you can easily fix it yourself. Additionally, PDFPen has a variety of useful editing tools including highlighting, underscoring, and strike through. It even includes a library with common proofreading marks allowing you to simply drag and editing marks to PDF documents before sending them back for processing or correction. This isn't as efficient as simply using a red pen yet, but when working electronically with someone in another state, you really can't beat it. You can also add notes and comments just as in Adobe Acrobat.
Another nice feature in PDFPen is the ability to use your digital signature. You can use a scanned copy of your signature and literally drop it in a PDF document before returning it to the sender. This provides a truly paperless option for entering contracts or other transactions. This works hand in glove with another PDFPen feature, the library. The library can hold frequently used images and information including your signature. If you work with PDF forms, PDFPen also will accommodate you. It allows you to fill out and save PDF forms easily. While it is possible now to delete pages and reorder pages using Preview, PDF Pen's implementation of this feature is much easier to use.
One of the improvements with the latest version 5 is the inclusion of optical character recognition. Often PDF documents, when provided you, do not have OCR already performed. PDFPen can now either automatically or a request perform its own optical character recognition on your document. In my tests, the performance was not significantly better or worse than that obtained with Adobe Acrobat. As with all OCR functions, it is a function of the original source document. If you have something typed, the OCR will be much better than if something is handwritten.
For $49.95, I believe PDFPen to be an excellent value. If you need to create your own PDF forms, you can upgrade to PDFPen Pro for $99.95. Another added feature at the pro level is the inclusion of the table of contents. This works with the "bookmarks feature" of Adobe Acrobat. I often send PDFPen bookmarked documents to my PC brethren who are none the wiser.
If you currently are using Apple's Preview application without feeling its limits, you're probably okay in terms of PDF manipulation. However, if you are running into its shortcomings or wish you had some of the Adobe Acrobat features without the Adobe Acrobat price, you should take a serious look at PDFPen and PDFPen Pro. You can find them at Smile on My Mac's website.
You can listen to this review on the Typical Mac User Podcast #161.