I won't say much about "Deep Space Nine" other than that it is the most well written, off-beat, and truly suspenseful of the Star Trek series. It is the series for everyone else... those who don't enjoy happy Star Trek (ie- "Next Generation), weird Star Trek (ie- "The Original"), or dumb Star Trek (ie- "Voyager").
It has a much darker tone, with a story-line that, if anyone watched from the beginning of the story arc to what is on currently, could understand and enjoy. It doesn't have the traditional "We are the Champions and can solve any problem in an hour". It features low-life, people making mistakes in judgement, conflicts over spirituality, and a much more human and less superficial look at one of pop culture's little universes. It features war-torn individuals and petty conflicts over land. Problems with culture-clash, government conspiracy and corruption, etc... This list could go on and on.
The main thing that makes "Deep Space Nine" different is that it is a Star Trek series for folks who don't want a lot of technobabble (not that there isn't any) Star Trek, where problems just go away or perfect people on a perfect ship that always win. It makes it more interesting for the watcher, almost like reading a novel. Most people, especially non-Trek fans, who had watched the series from its conception or joined when the story arc began about 4 years ago will know what I mean when I say this is an untraditional type of Star Trek. And those who haven't, try it. It's definitely a move away from the stereotype most folks have about the Star Trek series (though of the other Star Treks, I can't say the same.)
