I purchased the 2TB Linkstation Duo which is pretty similar, and though it's not perfect, I like it a lot and their service has been great (better than Apple's and better than my ISPs). Transfers go fairly fast (others are faster if that's a priority), it's small and quiet, after a little trouble setting up the sparsebundle the first time Timemachine works great (common problem, info is all over the web on how to create the sparsebundle manually), remote access works great from my iPhone, I have given friends their own folders to back up important things on, and have folders with pictures and music that they have access to see and listen to. Their admin interface is a little slow and clunky and could use some more flexability, but allows you to do most items such as allowing web access to certain folders and restricting permissions...though only at the parent level folder. You can't set permissions on folders within folders. I had some problems with getting my firewall to allow access remotely, I called my ISP, they were no help, called Buffalo and though technically that's not their problem they were very helpful and found a site on the web that contained screenshots of the proper setups for port for all routers and services.
This will likely be a bit too late for the original poster, but my experience of Buffalo support has been pretty bad. The current situation with my Linkstation is that they do not consider it a current model and therefore will not release a fix for OS X Lion compatibility, making it useless for Time Machine backups, and I can only access the drive if I turn off access control. The device was still on sale earlier in 2011, so how it can be considered old is beyond me.
On the up-side, the two Linkstations I own have been reliable up until now. Personally, next time I'll be going with a Synology NAS.