Like Clint, I need SFTP support. If it had it, FTPeel would probably become my quicky uploading tool of choice.
To be my main FTP app, I need to be able to edit files in place. In an ideal world I would just drag that php file down to BBEdit in the dock, make my changes, and when I save they would be uploaded. I already get some of this functionality with Transmit and BBEdit, anthough in a clunky fashion. It would be great to be able to edit any remote file in any Mac application.
Otherwise, it looks very slick.