The design goal of the 712 was to reach performance levels of '92 workstations
and servers at a fraction of their fabrication costs.
Everything was kept simple, the case is one of the smallest I have seen so far.
The whole system only has one fan which keeps everything quiet.
Because the 712 was the system with the highest production number you can get
these really cheap now. Their big disadvantage is the limited expandability: 

max. RAM of 128/192MB 
only one internal harddrive 
no internal CD/DAT/MO-drive 
only 8-bit graphics 
only 10Mbit Ethernet 
second Ethernet hard to find 

But in general they make great net-servers, they should have enough
processing power to deliver e.g. NFS serving; they also make really nice
HTTP/SMTP servers since you easily should be able to find a place for them
to run 24/7.
Very important is their limited demand for electrical power.
After a bit tweaking, the 712s can run headless (i.e. without attached
keyboard and monitor) so they are optimal candidates for light server tasks.
Nevertheless, the 712 are a really good choice for the desktop.
They are small, quiet and elegant (somewhat), you have everything you need
in one small box and the processing power even can cope with CDE under HP-UX. 
 
(www.openpa.net/systems/712.html)