The plot from this is lifted from the play/movie "Brigadoon"...though without all the singing, Van Johnson, Gene Kelly and the rest. When the story begins, the Defiant spots a planet that just appears! They are invited to land and learn from these nice folks that their planet appears and they live their lives every 60 years. Then, it disappears after a bit and becomes invisible and the folks go to sleep for another 60 years! It's actually a pretty ridiculous idea but try not to think about it.
During their visit with the nice folks, a VERY frisky guy from the magical planet seems VERY bent on getting his groove on with Jadzia Dax. Slowly, Jadzia also starts having feelings towards the guy. In fact, she's so taken by him that she agrees to move to the planet to stay with the guy. Ultimately, this doesn't work, as the writers weren't about to write her off the show...yet.
Overall this is a reasonably pleasant episode though it's hardly original. Worth seeing but forgettable.