Even the parts with Rom, this was the first time that I actually thought of Rom as a well defined character and not some sort of caricature of a Ferengi. In Emissary, The Nagus, and Rules of Acquisition, Rom was simply a mindless talking head that would do the "typical" Ferengi actions and be subserviant to his brother.
In this one, we actually find out that Rom has a brain, and this foreshadowed his usage later in the series. If we hadnt had this type of ep for Rom, then he might have been let go by the wayside as far as his involvement in storylines.
Off subject a bit, but I love this ep for other reasons as well. Currently I'm reading the Terok Nor trilogy and I gotta say that when first watching these 'Bajor' eps like The Collaborator, Necessary Evil, The Circle Trilogy, et al, I wasnt nearly as invested with the characters as I am now. I'm genuinely looking forward to when The Collaborator comes on again, even if all I want to see are a few minutes when Kubas Oak is thrown into a holding cell.