Touching on some of the same themes as TNG's depressing fourth season episode, "Suddenly Human", "Cardassians" is about another hard-luck custody battle - but it's notable for bringing back Andrew Robinson in the B story, built around the continuing relationship between Bashir and Garak. The pairing is gold, and their scenes engaging as the first time around.
The Cardassian boy himself gets the A story, with Vidal Peterson playing the kid with a mix of anger and frustration any boy his age would have in this situation. He gives the adults something nice to play off of, but because of the heavy subject matter, some of the scenes are slow and awkward, and it takes the plot a while to get moving. (It might helped had the show cast a younger child as the Cardassian boy to allow the character to be less sulky and more innocent. The downside would be that his relationships with the adults would be less complex; but the episode doesn't really take the time to explore these anyway, and this would allow for more of the focus to be on Garak and Gul Dukat, the latter of whom is excellent as the episode's heavy, even if his evil plan is more convoluted than that of a Scooby Doo villain.
With a nicely laid out story and some backstory for the station, "Cardassians" is a fine episode, but not much more.