FTP over WWW

Ever had the problem of sitting behind a firewall and no being able to connect to a server via FTP to upload/download something or to update your private site from work? Maybe you should give www2ftp.de a chance, an FTP program via Internet.
And at least they say that they are not interested in any files/passwords and that everything gets deleted immediately after your logout.
I haven't tried it yet, but its nice to know about it. Anyone got already experience with it?