• Background transfers (2.1+).
• Resume support.
• FTP compression (MODE Z).
• Media scanner support.
• FTP over IPv6 support (2.1+).
• Compress and decompress zip, tar/gzip and gzip files.
• Backup sites to SD card.
• No ads.
• German, Dutch, Swedish translations.
• Create shortcuts to sites on the home screen.
• WebDAV support in version 2.4+.

Note: If you are upgrading from the free version make sure to export your sites before you uninstall!

FTP Express support and feedback group:
https://groups.google.com/d/forum/ftpexpress
If you join this group you are also eligible to become a beta tester.