I have been using Paperpile for last 20 days on iOS platform and I am absolutely loving it !! However, I think some important features would make this app even better.
- A sorting function to sort the papers in a library (e.g., sorting based on year of publication)
- Share a paper through link/email (super useful).
- Adding multiple PDFs to a paper (e.g., preprint, supplementary, and personal note etc.)
I am sure there are many more, but these are essential I feel.