This episode is mainly a set up for 7:22, but it still has much to offer.
Memory Alpha has a short summary here.
Obviously, what I like best about this episode is the role the writers craft for Kira -- a role that is precisely as ironic as Sisko suggests. "You want me to go behind enemy lines and teach a bunch of Cardassians how to be resistance fighters?" she asks early on, her voice colored with a distinct - and hilarious - skepticism. Over the next few episodes, however, she's given plenty of opportunities to prove that she's the woman for the job. Number one, she's smart, pragmatic, and even a little ruthless -- but as she correctly points out to Damar when the latter hesitates on the matter of hitting Cardassian-guarded targets, the Dominion would be all too happy to take advantage of an attack of scruples. Number two, she actually can restrain herself. That she destroys a room full of supply crates instead of bashing in Rusot's skull certainly indicates her capacity to set old wounds aside and focus on the matter at hand. (It's also a very funny scene. "I'm glad we're in agreement." "You want to knock over some supplies, be my guest." LOL.)
We also have Dukat's blinding (which takes both him and Winn out of the picture until the finale), Gowron's attempt at self-aggrandizement (which doesn't really pay off until the next episode) -- and we have the Big Revelation regarding the source of the Founders' illness, which I imagine is hugely controversial in the fandom at large. I too would rather not consider the possibility that citizens of the Federation would attempt genocide, but this is a good example of what I mean when I say that DS9 tells the truth. Even fundamentally benevolent organizations have their bad apples -- and I think it's important to remember that for every Sloan, there are about a thousand Julian Bashirs out there who are horrified at the thought of using a sentient being as a bio-weapon. (Because as bad as genocide is, I feel less sympathy for the Founders than I do for Odo, whose very autonomy has been violated.)
Overall, as transition episodes go, this is a cut above the rest. Echevarria makes at least two brilliant calls here for which he deserves credit despite the uneven payoff in future episodes.
See the discussion above.
The script is held up beautifully by an excellent ensemble performance.
The writers continue their exploration of what is and isn't permitted in wartime -- and once again, they ask questions instead of providing pat answers.