Overall Rating: 8.0
The introduction of Section 31 to the Star Trek universe was a brilliantly provocative idea and the episode in which this revelation was made was well executed - though, granted, the basic idea of a holodeck simulation designed to fool you into thinking you're among friends but the program flaws give it away is not new.
The full (and alarming) details can be found at the all-knowing Wikipedia.
First, let me just say that DS9 makes me so happy. It undermines all of those fluffy "holier than thou" feelings immature Trekkies get for their liberal ideologies while atching Picartd bloviate on TNG and I LURVE it. Here we go again with DS9 undermining that last shred of pretension...we can't wag our fingers at the Obsidian Order or the Tal'shiar any longer...because it turns out...we have the same damned thing. MWAHAHAHAHAAA!! OK...that's enough gloating. Anyway, Bashir's condemnation of the crooked organization ought to at least put to rest any fears of moral relativism (ends do not justify the means...that's a Russian conceit) and their tactics certainly don't leave you with a warm fuzzy feeling for intelligence gathering organizations without public oversight. But it is nonetheless refereshing to see the Federation as an organized government run by adults and not starry eyed children.
I never really got into the "Sloan" character as a rival for Bashir - they were trying to create someone who was exactly like Bashir if Bashir had no conscience...but they rather whiffed. I think Sloan would have been a better character if we'd have spent a little more time developing his background and seeing the similarities and the rationale behind his decision to join Section 31. That said, even without great characterization, Slaon does play the role of foil well here if what he's reflecting is Starfleet morality in the face of common sense. How indeed can the Federation survive if all of its' enemies don't play by our sense of rules and fairness? It's not a simple problem and there are no good answers to that question...though I'm fairly certain that Section 31 is the worst possible response besides surrender.
The particulars of the episode were, perhaps a little over the top. The change from station-wide support fo Bashir to station-wide loathing wasn't quite sublte enough...though they did try very hard to sucker us into believing the illusion. I would also have preferred a different mechanism for delivering the illusion. The TNG episode "The Forgotten," in which Riker wakes up and is made to believe that he's lost 16 years of his life for the entertainment purposes of a lonely alien child bears too many similarities with this episode not to be noticed and feel a little cheap. I would think an organization like Section 31 would have ways of interrogating a man entirely inside his own head a la the Romulans...and I would think they wouldn't be above a little more torture. Bashir should have awaken from the interrogation in restraints and had devices painfully extracted from his head, etc. But...perhaps that was a little darker than what they were going for. Alas.
They missed opportunities to really "go there" and deliver something landmark and terrifying. What we got was a little on the repetitive and light-touching side for such a dark concept. But the concept itself and Bashir's reactions to it were still well worth the viewing.
Alexander Siddig put in a fabulous performance, as did Colm Meaney...Sloan was a bit on the "meh" side, as was Avery Brooks, and that keeps my reaction muted.
We'll give this one credit for blurring the black and white morality of Roddenbury a little further still and for poking liberals in the eye...but a future Section 31 inspired episode "Inter Arma Einem Silent Leges" will do it better.