Back in the day, there was a lot of excitement about Commander Riker crossing over into Deep Space Nine just as the first TNG movie was debuting in theaters. Turns out, it's a swerve! But while this seems like a letdown at first, the end result vindicates the choice.
"Defiant" is a chase episode with Riker (in the titular ship) as the prey and the Cardassians as the predators. The twist (inspired by the 1964 film Fail-Safe) is that Sisko joins the Cardassians in their war room to help catch his ship. This gives Avery Brooks a chance to shine and gives us a peek behind the curtain at Cardassian politics, with Mark Alaimo guest starring as Gul Dukat and Tricia O'Neil guest starring as Korinas of the Obsidian Order. The set for the war room is especially nice, with a large viewscreen helping to tell the story in a way that doesn't break the bank. (What's really amazing is that this viewscreen is actually a miniature, though you'd never know it).
The components all work well together, with the Ron Moore script progressing in a way where the story just keeps getting more interesting. The end result is a military thriller on par with the original series episode "Balance of Terror". The story even plants the seeds for a sequel, but for whatever reason this idea was literally blacklisted by the show's producers afterwards which is perplexing, since Frakes and Nana Visitor (Kira) have mad chemistry with each other. (Rest assured, however, the fallout of this episode reverberate into the future).
Fans looking for a great Commander Riker episode might be disappointed, but Frakes is fabulous and fans of the actor won't be.