The advantage of both the Simple NAS and Net-Stor over most other consumer NAS is that you won't be stuck with a brick if your NAS' hard drive dies. All you need to do is replace the dead drive with a new one, format it, restore your backup (you do have one, don't you?) and you're on your way.
In addition, both products are also among the least expensive NAS alternatives around. The low cost comes from the cost of the products themselves and due to the fact that they use relatively inexpensive 3.5" drives. BYOD alternatives such as the Linksys NSLU2 and ASUS WL-HDD 2.5 are slightly less expensive for the boxes, but require more expensive USB and 2.5" IDE drives respectively.
But sometimes you get what you pay for. Both devices have smaller feature sets, lower performance and noisier fans than more expensive alternatives. The Net-Stor also lacked backup software, timed drive spin-down and even the ability to get IP information from a DHCP server. And the Simple NAS' inability to set user-level privileges and very slow read / write speed won't impress many buyers.
If you're on a budget and you only have light-use requirements from your networked storage, either one of these boxes might do the job. But more demanding users would be better served (!) by more fully-featured models.