Despite Rene Auberjoinois' fevered overacting and the extremely disappointing resolution to everything that was going on, I find myself enjoying this episode. That might just be because I find the Cardassian-ruled Terok Nor of the past such an interesting place and want to know more about it. Visually, it's really amazing. Plus, we get Garak and Dukat back and they both just make for compulsive viewing. Dax is also on fine form as she adapts to the role of scared Bajoran with ease, and then single-handedly mounts a prison escape.
Plus, guest start Kurtwood Smith is just fantastic, as always.
But yes, the episode has big problems. Odo just acts strangely and lets us know that something is up from the very start. And the explanation of why this "time travel" happened at all is just nonsense. Also, the echoes back to the season 2 episode 'Necessary Evil' are so prevalent but this episode never once acknowledges it. Especially, the final scene with Kira and Odo is pretty much a mirror image of the one that ends that episode, so why don't the two of them bring that up and realise that they both did bad things back then instead of Kira being all high and mighty?