If ever there was a STAR TREK that could have been done as a daily soap-opera, DS9 was it!!!
To a point, though I'm glad the writers didn't get too carried away with soap opera-style stories. That basically started to happen a bit at the end with the Work/Jadzia/Ezri/Julian storyline, and I don't think it worked very well (outside of a few moments such as the classic scene where Worf breaks Weyoun's neck).
I really enjoy how the large-scale conflict with the Dominion developed over the course of five seasons. This is an obvious strength of the show, along with the large number of interesting recurring characters.
On the other hand there is the downside, which is that the characters were increasingly isolated into little sub-families in the later seasons. Basically, you had:
-Quark and the Ferengi
-Worf, Dax and the Klingons
-Kira and Odo
-Julian and Miles
-Sisko, Cassidy and Jake
Not that there was never any overlap, but generally you had either the crew acting together on some mission or other, or you had an episode focusing on one "family" or another. What got lost in the shuffle were those relatively minor but very entertaining relationships that really carried the show in the early seasons. Relationships like Odo/Quark, Odo/Garak, Kira/Sisko, Sisko/Dax, Kira/Dax, Quark/Kira, Quark/Sisko and so on.
My favorite seasons of the show are 2, 5 and 7. One of the reasons that 2 is up there for me is that season 2 is the heyday for a lot of those little interactions between members of the main cast who often don't really get along and don't even like each other much yet, so they're always arguing and getting on each other's nerves. There's a lot of really good dialogue in the early seasons that's often not even integral to the plot, just produced by the characters being played off one another (Odo/Quark is a great example). A lot of that gets lost in the shuffle in the later seasons, though they are great for other reasons.
Incidently, the character that got hit hardest by this tendency was definitely Quark imo. He's so important to the show in the early going because his character and his bar really set the stage for a lot of those great little scenes I described above. By the end though, he really doesn't have much to do if it's not a Ferengi episode (notice that none of the rest of the regular cast are in his "family.") He's the only character who can't really be brought into the Dominion War on a consistent basis, and even his bar gets replaced often at the end by Vic's (a bizarre and unfortunate decision imo).
So yeah, I think Quark really got marginalized, but other than that most of the characters made the transition well.
