Three Klingons arrive at DS9 with a plan of revenge in mind.
This is a good character development episode for Jadzia Dax and a nice tribute to the original series.
The plot is simple and engaging with Jadzia placed in a compelling situation due to the history of the symbiont Dax. For me it all boils down whether Terry Ferrell convinces you that her character has the mentality of a Klingon warrior due to Dax's association. For me she just about does it and that is why the episode works.
It is great to see John Colicos, Michael Ansara, and William Campbell back on screen after their memorable guest performances during the sixties.
Star Trek has traditionally been about positive resolution to conflict with the avoidance of violence, however the Klingon cantered stories have been a way for the writers to have their cake and eat it when it comes to these themes. As DS9 goes on it only gets darker in certain episodes, so if you have a problem with this aspect of the show, now is the time to jump off.