What do you like best?
We use it to generate fillable forms for customers - it works very well whether inserting date or image.
What do you dislike?
The document management part is a bit confusing. It can be difficult to work with templates vs documents, and with shared templates or documents.
What problems are you solving with the product? What benefits have you realized?
PDFFiller has made generation of forms - both using their web app and API, extremely productive for our operations team.

What do you like best?
The ability to edit practically any document, within reason. As a Finance professional, it's much easier to add a JPEG of a signature to hundred of checks rather than signing them by hand. My carpal-tunnel free wrists thank you!
What do you dislike?
I don't have any negative comments; everything that the program promises, it delivers.
Recommendations to others considering the product:
It's a great value for a relatively low monthly cost.
What problems are you solving with the product? What benefits have you realized?
It allows for rapid addition of signatures to checks, contracts, affidavits, etc.