I love Paperpile. Before paperpile, I use EndNote for my PC. However, my EndNote is not compatible with my Mac so I have to buy a new version. My friend told me about Paperpile, and I love it. One of the best feature is that I can change my citation style to any style I want. And the software will update entire file to the new citation style for me. That is a wonderful feature. Additionally, another plus is that Paperpile is compatible for both Mac and PC, and it compatible for Google Drive as well. Lastly, I can embedd my reference simply by looking for the title. This feature is much better than Endnote, where I have to download the file and embedd them into my paper. Sometime, if I have 200 references, the amount of files I am downloading can be overwhemming.
Nothing. I love paperpile. They are very easy to use. Sorry, can't help you there!
Althought, if you can make it run faster, that would be great.