Imagine getting a document via email. You want to make a couple of corrections and send them off to get corrected. There are about 3-4 steps involved in doing this on the iPad.
Now, from within Mail, you can open in “Sign-N-Send” and make annotations, handwritten mark ups or add you signature – Then, send the document along.
Now, you can scroll through a pdf and choose from various pens, highlighters, etc. to mark up your document. It handles multi-page PDFs fine. When you send the marked up document out, the program appears to convert the document to an “image” PDF (like getting a fax). Basically, if you send it a readable OCR’d document, you will lose the ability to read it via search on the receiving end. You can still see it fine. You can re OCR the document if necessary on your computer.
To the left, you can see where I sent a 19 page PDF that was 33 kb. I marked it up without any effort using the drop down tools. You can see that pen choices, highlighters and even a text annotation are possible.
When I sent the document back to myself, there was a conversion process. On the receiving end, the document was about 2 mb.
Since the App is free for a limited time, I think it is definitely worth trying out.