Relatively quiet and sturdy build.
RAID 1 pointless without the ability to replace a drive or repair an array.
As a single disk device, I see no reason not to buy the Shared Storage II. It has a sturdy build quality and is relatively quiet. It might be lacking some features other similar products, but will do the job most require.
However, the 1TB model that uses two 500GB drives in RAID is a quite a risky device to store your data on.
What use is RAID 1, data mirroring, if you cannot replace a faulty drive or rebuild the array? The Shared Storage II can do neither. RAID 1 in this device only serves to half the volume of the device.
RAID 0, data striping, is equally foolish in this device. It doesn't allow you to access your data faster. Rather it serves only to put your data at higher risk of corruption.
Data or array issues is a higher than normal risk with this device because it uses software RAID rather than hardware (chip-based) RAID. Normally such issues are easily fixed if they occur, but the Shared Storage II lacks any interface to do so.
If the 1TB model had the option to use the disks without striping you data would be safer. And lacking the ability to repair and array or replace a faulty drive means it's impossible to recommend this over any other NAS that does include these features.