It's always strange to get a PogoPlug-based device. No install CD or discovery software. No way to tell from the outside the IP. To set it up, you head to the rebranded website (cloudstation.pogoplug.com, in this case), follow the steps and then everything becomes available to you through the web interface. It pitches itself as a "personal cloud", rather than being a NAS.
True techies are likely to balk at the lack of control and direct access to the device. Unlike other PogoPlug devices, though, Buffalo gives you full access if you're willing to jump through a few hoops. You'll need to find the internal IP first, by going to the system section of the website's control panel, and then you'll need to set the device password. After this, you point your browser to that IP, enter the password and you'll have local access, and the ability to set a manual IP.
Never fear; whether set up locally or through the internet, if you're on the local network, file transfers will take place there, for speed and for the sake of quotas.
Once you've done this initial set-up, you can access files on your device, upload to it or download clients for Windows, OS X, iOS and Android. You also have access to PogoPlug cloud, a free 5GB of space hosted by PogoPlug itself, which functionally acts as a Dropbox competitor. You can upgrade to 30GB for US$4.95 per month, 100GB for US$14.95 per month, or 1TB for US$59.95 per month.