The bundled dLAN Cockpit software is used to manage compatible attached peripherals - be they printers, scanners or storage devices. A lesser issue, but one that affected us, is the lack of OS X and Linux support - the DeVolo Cockpit software is supposed to be available for these operating systems, but a release is as yet still not forthcoming.
To its credit, this interface is surprisingly easy to use. As well as showing a faux-map (obviously the software doesn't display the physical location of your adaptors) you can name adaptors, add new adaptors by their id (printed on the device). If you have other DeVolo adaptors, the Cockpit even shows you the data rate between them and will suggest ways to improve it if it's particularly low.
For all of the fanciness of the UI, however, the DeVolo dLAN 200 AV USB has a few issues. For a start, it's perhaps disappointing, but not unsurprising that the DeVolo dLAN 200 AV USB isn't just able to present remote USB devices as if they were natively network-accessible. So although you can access USB storage devices from a computer, there's no DLNA streaming - a feature that a number of USB-equipped routers do offer. And similarly there's no web access to attached storage, another feature a dedicated storage system would likely offer.
This might be acceptable if the DeVolo LAN 200 AV USB adaptors were cheap, but they're far from it. For not that much more than these adaptors you can get a Verbatim Gigabit NAS (or a number of similar systems) that throws in a terabyte of storage to boot - and can have external drives and printers attached to it. And with this solution If you decide you really need powerline Ethernet you can always add adaptors later.
The DeVolo LAN 200 AV USB adaptors sound like a great idea in theory, but in practice they turn out not to be that useful. Where Ethernet-over-powerline is almost universally useful, USB-over-powerline has a way to go before it's a particularly useful technology.