This claustrophobic episode focuses on Ezri's adjustment to her new circumstances and everyone else's adjustment to Ezri Dax and the casualties of the war.
The Thrill species can have joined symbiotic relationship where the symbiant outlives the host. Ezri is thus the 9th host and shares the memories and feelings of the 8 previous hosts including Jadzia who was an integral part of the station and the show for the last 6 years and the wife of Worf. This particular situation makes for some great drama trying to figure out how to interact with someone who has the memories and feelings of someone you know but that isn't that person. This is what science-fiction does best and DS9 gets Les Landau to direct actors who are as familiar as they can with their characters in the show's last season and put new wide-eyed and confused Ezri Dax (and new actress Nicole De Boer) to thread the line between this complicated situation.
Add Andrew Robinson as the enigmatic Elim Garak for character development and repartee, quirky Quark for warmth, brash Bashir for flirty friendship and bravado, as well as Avery Brooks' Sisko who not only knew Jadzia Dax but also Curson Dax, the 7th host. We have all the complexities of a great chess match and an episode that is perhaps match by "Duet" as one of the best Thrill episode ever. One of the best and most difficult episode all together when you take into account the 6 year backstory of all the characters culminating into this unspoken conflict (or conflicts).
The dialog and story are strong but the beauty is really in the nonverbal nuances, the tone, the double entendre and deeper interplay. In that sense, the episode may be for DS9 connoisseurs instead of passerby, but it still showcase strong narrative impetus. Also it elevates itself by the quality of questions it raises and the satisfying yet not quite resolved resolution.
Ezri is in search of herself, but we are glad we have found her. A great character and circumstances episodes to make Ezri Dax a solid part of the final chapter of this space saga.