Windows Phone 8.1 "looks" similar to 8.0. BUT, it's a completely different beast underneath. It unleashed Windows Runtime to Windows Phone developers. It's optional and requires extra steps, but adapting it tremendously helps us developers easily and efficiently target two platforms, Windows and Windows Phone, at the same time.
We have been taming this beast; rebuilding in-house libraries, experimenting with new and unique user interfaces and etc. And we now finally have a brand new 8.1 app, Fil3Tr33!
When you start Fil3Tr33, you'll definitely notice our unique user interface elements such as the top path bar that automatically hides itself when you scroll up the listing; showing you more entries instead of blocking the view.
Our Share server engine also has been improved and it now includes its own name server; you can use a "name" to access Fil3Tr33 Share server and you no longer get that annoying security warnings when you copy or move files from the server.
For your information, our Share server engine that turns your Windows Phone into a SMB file server is our own creation specifically designed and optimized for mobile platforms such as Windows Phone. It is lightweight and runs within the security boundaries set for an app; you definitely don't need to jail-break or root your phone to use it!