I haven’t watched Enterprise, so I don’t know what that show’s MU episodes are like, but I have seen most of DS9’s and I disliked almost all of them. The first one was alright, but I quickly grew bored with them; neither the DS9-era Mirror Universe nor its inhabitants were all that interesting.
I feel this is the only worthy sequel to Mirror, Mirror. Pity no one thought to adapt it to the screen.