This is an incredibly useful plugin as I needed something that I could upload files for my users but still keep them secure. This does that perfectly as you can set permissions on individual files, and also the root file path is secure so nobody can copy and paste the link to go directly to the file without logging in.
Another great feature is the custom templates, as you can display files using the shortcode exactly as you want inc. thumbnails, file size, date uploaded etc. Also the File tree system works well when you have a larger amount of files to display. The only thing it's missing to make it perfect is to be able to track which users have viewed/downloaded files.