Hi, Atra.
Yep, the deep space one was truly an innovative little testbed probe. You don't often hear NASA actually doing anything risky or innovative tech wise. But this is one example of them puttting together a set of great ideas. That and trying to replicate that russian scientist's gravity work in Scotland. They do have high risk programs but they tend not to publicize them for fear of uninformed criticism and subsequent danger to thier already meager budgets.
One of the ways plasma is neat is that if you run it through the center of a coil, the moving plasma (ions) induces a great deal of current which can be used to power things on the rest of the ship.
A bad thing about ion drive so far is that the acceleration is so gradual. It takes a great deal of time to build up speed. That being said, ion engines can develop more thrust than chemical rockets if given enough time. Making them ideal or the first inter stellar probes to such places as alpha proxima (of alpha centuari triple star system) 3.9 light years, Barnard's star 10 light years and other nearby stars.
Of course, it is always possible that we will be able to increase the ion density and fix the current acceleration lag. If we perfect linear fusion or perhaps AM reactors. In that event we'd be well on the way to TOS technology levels. In many ways, communications, computers and so forth we are already ahead.