Apart from the highly impressive hardware feature set, the main attraction with the WL-700gE is its in-built operating system. Based on a minimalist Linux build, the onboard OS is embedded into the firmware and takes over the full capacity of the hard drive.
At a basic level, the router functions as an UPnP NAS device. The hard drive has a pre-defined file structure for downloads, music, photos, videos, web files, ASUS utilities and automated USB copies. The drive is available via UPnP once the initial router configuration has taken place. No special software is required to access the drive - a connected client running TCP/IP, the Microsoft Client and the File and Print Sharing protocol (the basic Windows networking setup), will be able to connect. For Linux and OSX users, the router uses CIFS as its default network file protocol and it also supports NFS. In a worse-case scenario, the drive's contents are also accessible via FTP or the router's web-based admin page.
Logging into the admin page, you're presented with the four main components of the router OS - configuration, share browsing, personal webpage and Download Master. They're all quite feature-rich, so it's worthwhile looking at them individually.