Well, 1.5TB+ drive support is spotty and only in Beta firmware. The UPnP AV server ignores configurations and just shares everything on the drive. Also: the iTunes server is audio only, network writes to it are slow, Jumbo frames actually appear to slow down most transfers, there is no NFS or AFP, most Raid creation hangs at 94% for several hours, Raid drives are often initialized with corrupted partitions, and some of my Macs reliably freeze it with the latest firmware to the point that I have to pull the power cable (which put the Raid in a day-long rebuild). I also hear that Active Directory support was claimed in the last Beta release and is supposedly not working, but I have not tested this specific bug.
And to top it off, they have been really, really slow at releasing updates. Yay!
Official D-link people, please read this and rally your developers. The DNS-343 is in sad shape.