I started watching Deep Sleep Nine--um, sorry, Deep Space Nine--when it came out, purely because it was Star Trek. I enjoyed it a lot of the time, and appreciated Star Trek's attempt to try a somewhat different format. I liked the fact that there was an ongoing background involving Bajor and the Cardassians, which gave a greater feeling of continuity and flow rather than the villain of the week prevalent on TOS and TNG. I've always liked Rene Auberjonois, so I was glad to see him, and I liked Nana Visitor from the very beginning.
My only complaint was that Avery Brooks seemed to be behind a glass wall for the first few seasons. Later, Avery started to get fired up, and the show gained energy. And I was glad to see Worf--he is such a great and fully realized character, and I think Michael Dorn does a brilliant job with him--but there was really no plot-related reason for him to be on the station. They handled that badly. He seemed like a supernumerary, and if he were any other man
he would have been completely extraneous. Fortunately, because it was Worf, they made it work.
I lost touch with it toward the end because I wasn't home the night it was on, so I know very little about Ezri or the resolution of the Dominion War. Overall, though, I thought they started slow when they first launched but before too long they were making a really compelling and contextually rich show.