What do you like best?
As a Realtor, my whole business is based on electronic documentation. PDF filler is kind of named poorly, because it really is a PDF editor. It allows you to easily change almost anything on a pdf document...across both desktop and mobile platforms. It simply works as you'd expect it to...every time. I use it practically every day.
What do you dislike?
I wish there were better tools for generating lines (how about a toggle into and out of orthagonal for a line?) It should allow deeper zooming with a thumbnail view showing where you are in the overall document. I like my pdfs to look perfect and sometimes these limit me in that goal.
What problems are you solving with the product? What benefits have you realized?
A Realtor literally lives or dies on his/her electronic documentation. This tool lets me master the changes that inevitably occur with documents. I use it every day.

What do you like best?
I like being able to edit and/or fill-in .PDF documents. I also like that I can retrieve documents that I have previously worked on.
What do you dislike?
I'd like to be able to change the font in the text option, as it doesn't always look right if mismatched.
Recommendations to others considering the product:
I'm not sure how I first heard of PDF FILLER, but am I ever glad that I found it. My advice would be to try it out and see if it suits your needs. I like many of its features, especially the left pane that shows the document pages, and the ability to select only those that you want to include in a print or save maneuver.
What problems are you solving with the product? What benefits have you realized?
One use that I have for the program is for one of our telecommuter workers - so that she can enter details on employee time cards, and it looks better than handwriting in notes. Uploading the documents she needs is a breeze, and the program alerts me to activity, for example, when she emails the documents to us for distribution.