If the Armada line had included a second run, or even a larger first run, then my collection of Armada sets, which consists only of 6244 Armada Sentry would be slender enough to have merited the theme a spot on the list of "Ones That Got Away." As things stand, however, LEGO only ever released two sets in the Imperial Armada line, with three distinct figs, and a total of four figs overall. Less than half a dozen other Armada figs would appear in contemporary (1996 and 1997) Pirate sets.
Despite this very limited run, the Imperial Armada was a beautiful line, as LEGO's only foray into the era of the Renaissance--albeit in the Americas, under the auspices of the conquistadors. The minifig heads and torsos are excellent additions to Castle or Pirate collections (and useful elsewhere), and were never used in any other theme.
I got Armada Sentry for Christmas in 1996 from my grandparents, and I would remain the entirety of my Imperial Armada collection until the Bricklink era, when I eventually put together a second fig. In the meantime, I acquired enough of the helms to arm the Jayko Armada figs seen in this post. All told, though, my Armada faction is all of five-men strong, and remains based at the little fortified dock of Armada Sentry.
It's a lovely set, if a little one. For it's size, it contains a wonderful variety of pieces, nearly all of which (if not, in fact, all) are generally useful, including the green doors, which are exclusive to the set, and the 8x16 blue baseplate. Perhaps the least useful pieces one would find in acquiring multiples of the set are the 1x5x5 wall/window pieces, which tend not to be popular with advanced builders, but even those are far from "useless," merely "fewer uses."