The biggest problem I have with the episode actually stems from something that on the face of it I applaud - good use of continuity. The fact that Romulan warbirds have quantum singularity engine cores is an important plot point carried over from TNG, but it raises the question - why did none of the central staff suspect a Romulan ship? Given all the TNG plots about them, surely Starfleet officers should be proclaiming "Romulans!" if their socks go missing at the laundrette, yet alone if a quantum singularity is mysteriously orbiting a Federation outpost while Romulans are actually onboard.
Still, at least it was nice to see the Romulans, as a follow up to their deal over the cloaking device.
And given that I share the Odo/Kira love love, so to speak, it's amusing that the Romulans have guessed how he feels.