The UI is outstanding and very effortless. Very impressed. My only issue was with advanced features. Would have liked to know ahead of time that they were additional fee. Everything looks included and don't like being told something cost money after the fact. Second, when telling me I had to upgrade to get additional feature, it should show the difference between what I am paying verses the new amount. I was on personal plan ($6) but to get the features I needed it was ($10). It said it was $10 for advanced plan but I didn't know if that meant $10 MORE than I was already paying. I had to open site in incognito mode, look at plans to figure it out... not fun. Lastly, I was trying to send 2 separate PDFs as one doc. It took me a while to figure out where Merge was. I didn't understand why all the options under Actions were greyed out. That was very frustrating and should be improved.

Found it difficult to navigate through at first but after using it a few times I figured out what I needed to get done but I'm sure there are easier ways to do things in there....

I did not know about PDFfiller.com but once I found it and realized what great features were offered and how easy it was to navigate and use, I was definitely impressed. I love the features since I work a lot with PDF documents and now I can make corrections or additions without recreating the entire document. PDFfiller makes my job much easier.