Up until this point, Captain Sisko's grappling with his anointment as the Emissary of the Bajoran Prophets has been a recurring theme in this series. Though obviously uncomfortable with this messianic role, he'd accepted it out of both practical reasons and respect for the Bajoran people.
The arrival of the Bajoran poet bails Sisko out; he's glad to concede the Emissaryship to the new guy. The problem is that the new Emissary has a very strong vision for Bajoran society -- he wants to bring back a very strict caste system that Bajor had before the Cardassian Occupation.
The Bajorans are somewhat shocked by this announcement, but most of them try to adapt as well as they can. Major Kira announces her resignation and begins to explore her "heritage" as an artist. (Without much success.) Sisko becomes alarmed once he realizes that the new caste system will disqualify Bajor from Federation membership. Things get even more out of hand once a man is murdered for refusing to adhere to his caste.
It's an intriguing premise, but the writers waste a good opportunity. Sisko tries to reclaim his title; he and the poet go to the Wormhole and the Prophets settle the dispute by reaffirming their original choice.
The second plot of the episode -- O'Brien readjusting to life when Keiko returns to the station (with a second child), after a long period of effective bachelorship -- is not very interesting. But it does generate the two best moments of the episode Worf's response to the suggestion that he'll deliver Keiko's second baby (hilarious!), and Keiko's clever plan to reunite Bashir and O'Brien.
Also, I enjoyed the scene at the end of the episode where Kira presents Sisko with one of her "statues".