Adding Worf in season 4(?)was probably good for viewers but I thought rehashing the Klingon stuff was a bad idea. Did we really need to see him outcast again. But I did like the addition of General Martok.
I always wondered why the Borg never showed up besides in the pilot.
I've read the books that came out since the show was cancelled overall pretty good. I highly recommend Avatar and Rising Son. I just got Warchild the other day. Hope it makes sense since I skipped The Worlds of DS9 books.
I do have to say that Garek is my favorite character.