What do you like best?
Frantically searching for a way to fill out a PDF form without losing all of your work? PDFfiller works great, does just what it says on the tin, and has the best customer service I've experienced with a website.
What do you dislike?
Though I was wary of a paid service at first, their customer service was as helpful as any I've ever experienced and the product works as promised.
What problems are you solving with the product? What benefits have you realized?
Filling out forms as a graduate student working far far away from campus, PDFfiller helps me get it all in order without a struggle. It simply makes life easier.

What do you like best?
The ability to create a document, upload a document, search and find document files, edit, and then fax or email to anyone anywhere right from the convenience of your laptop anywhere in the world. All documents created are saved in your account for return access, and activities (fax, email and receipts for delivery) are also recorded and saved.
What do you dislike?
So far I have not discovered something I do not like. I have uploaded, created, searched for online documents to use, and both faxed and e-mailed documents without an issue.
What problems are you solving with the product? What benefits have you realized?
Can work and send from home, work, on the road. No need to hunt for a fax service / company; no need to leave where I am at to go fax a document; can work and send documents in the middle of the night right from home or while on the road; have been able to search and find online documents and upload into account for editing use; easy to share documents via PDFiller; you can send documents to anyone with an e-mail address - your recipient does not need to leave their laptop either!