the author is no longer maintaining Net::SFTP. the last release was in 2005. several bugs exist in this package, including documentation that conflicts with the implementation (see RT #27586). this package also uses wantarray (a transgression amongst interface sensibilities).
This is a totally handy module, that puts a nice interface over the top of SFTP. Used in conjunction with the Net::SSH::Perl module, it's a great way to automate common file transfer tasks.
The one issue I have with it, and it's fairly major, is that it is quite slow compared to just using the sftp or scp clients provided with OpenSSH. This is likely not a problem if the files you are transferring are small; if they are large, though, it may be. YMMV.