Out of curiosity, what were things that these systems did poorly or that we know not to do these days?
Security was literally nonexistent. If you were at the console, you had control of the machine. Pwning one over the network was probably not difficult, though it wasn't the kind of thing people spent much time on back then.
But given the level of expertise which would have supposedly been their target market, wouldn't this have been an ideal environment for security analysts to develop within?
If you buy into the sales pitch, highly trained teams of developers would be properly outfitted with workstations well-suited to roll their own crypto, for development purposes, and then easily test against a wide array of complex scenarios.