JALSHERM  This is the BEST program for viewing, and editing PDFs. It is easy to use and saves me several steps when editing forms, maps and documents!  
(Version 4.1.3)

BRUSKI2007  I have been using PDFPen for a couple of months now and have to say that the set of features is excellent. I mostly use this app for deleting pages and its OCR features.

However, I find it to be extremely buggy. It is almost impossible for it to do an OCR scan of any sizeable document without it crashing. If it doesn't crash it usually hangs, forcing me to force quit the app. If the bugs were crushed this would deserve the full five stars but it is not there yet.  
(Version 4.1)

ALANTERRA  I just wanted to put in a short review saying how much I like PDFPen. If you are considering Acrobat Pro, definitely check out PDFPen--it might be better and cheaper for your purposes.

I first bought PDFPen for "light editing" of PDFs. Even though I own Acrobat Pro 8, I wanted a program that was specifically meant for editing pdf documents. You know when you have a form that has spaces that you are supposed to fill out--like with an IBM Selectric typewriter--PDFPen does that perfectly. It also assembles PDFs out of a group of separate documents, so you can take the form, delete the 3 pages of instructions, add the essay answer, paste in your signature and date, and just email back the final application without scanning or printing.

But, I just figured out today that the other thing PDFPen does well is that it "understands" multi-column documents. If you have ever tried to select text in a two-column document using Preview, you know what a PITA it can be. But PDFPen understands the document better, so you can select just the text you want.

I also use PDFPen to highlight passages in documents, just like reading a real paper document with a yellow highlighter in your hand!

I haven't tried the OCR yet, but have read that it is as reliable (or unreliable) as Acrobat's. I'll compare the two programs later.

But, in general, there is little that most of us need to do with a PDF that PDFPen can't do.

A

Oh, PS, I don't think it has ever crashed on me. I'm not sure I can say that about any other program I use (maybe BBEdit, not sure).  
(Version 4.0.4)

JOHN_ALLEN  Version 3.x of PDF Pen was a little buggy / sometimes slow for me. But still it got done what I wanted.  
(Version 4.0.3)

COBRA_BYTE  I've been using PDFPen for years and it keeps getting better and better!

I use it fill out forms and add my signature for PDFs that I need to endorse before sending them out.

Customer service is top-notch and I'll keep coming back to SmileOnMyMac products.  
(Version 4.0.3)

MITCHWILSON  Having purchased within 6 months, and being generally unhappy with this buggy software, I was more than disappointed to find that they want another $25 from me so soon. I would suggest waiting until they get the kinks worked out before purchasing.  
(Version 4.0)

SHARIK14  The last time I tried this app, it was still version 3 – and still dreadful, terribly designed, incredibly slow, buggy, regular crashes, and generally unusable.

The only thing that even tempts me to upgrade is the version 4 inclusion of OCR – but now I find that (despite the complete lack of utility in earlier versions) they want me to pay $25 for it.

No way, guys. I no longer trust you.  
(Version 4.0)

JFM  I have just bought the upgrade to version 4, and I am really glad I have done it: it is a major step forward, it makes handling pages much more pleasant with the sidebar showing pages and an easy way to change their size. Moreover, the general design is much more convincing than the previous versions. I was using it quite frequently already, although I didn't enjoy it too much. Now I feel that I will be using it more, but also enjoy using it: from a useful tool, it has become a nice tool.

(By the way, I posted this comment because I was quite perplexed to read previous comments about a "buggy" app: in my experience for the past 3 years, it has alway been stable.)  
(Version 4.0)

MTCOBRA  Interesting. I'm looking at the site for PDFpen 3.5, yet when I do Get Info, About, or Check for Updates on my PDFpen 3.4.2, it reports that I have the latest version.

Perhaps the inability to detect new versions is one of the things corrected or added in this new, 3.5 edition?

I recall having had to PUSH the update (rather than PULL) the last time I updated PDFpen.   
(Version 3.5)

JAYHAWKBABE  I, too, really want to like this application and was disappointed by it's speed, or rather lack there of, compared to Preview/Skim for even a small PDF file. I had problems with the PDF displaying funny at times, as well.

In the meantime, I use the FREE program FormulatePro. It's only on version 0.4, so there aren't a lot of bells and whistles, but you can type on forms and it's FREE. Very happy.  
(Version 3.4.1)