I think it remains plausibly futuristic, with many features that have -- quite remarkably -- kept up with scientific speculation about what an FTL spaceship might look like. I find it amazing that in trying to avoid the stereotypical science fiction shapes of the day, and the current thinking of what the near future might hold, Jefferies came up with something new and fresh and scientifically plausible.
It is only harmed in any way because it has become iconic and thus is no longer "new and fresh". But if it is used in the same context, then its iconic status only helps convey the point that this is Star Trek. Its plausibility remains in either case -- it is as believable as a FTL spacecraft as any in popular SF, and much more so than most of the modern Trek designs.
Remember (and I say this for everyone else Dennis, since I know you are well aware of this truth) uber-detailing and sweeping lines do not a plausible design make. Maybe visually interesting to eyes that crave detail, but no more plausible than a Death Star.
