I just saw the finale of Deep Space Nine and it was a perfect conclusion to the series- - except for one obvious blunder.
I loved the way they resolved the Dominion War. Most franchises would've killed the female founder on the spot for the atrocities she committed that episode, but I give a lot of credit to the writers for having her arrested and stand trial. Most won't find her punishment "satisfying", but having the villain face the legal repercussions for her actions feels very quintessentially in tune with the philosophy of Star Trek.
The conclusion of the Pah Wraiths sub plot is truly as bad as it's reputation makes it out to be. I was even on board with it at the beginning, and there were some good episodes to come out of it, such as "Covenant" and "The Assignment", but the fact that the Pah Wraiths storyline was dealt with in such a underwhelming and mundane manner, makes me suspect that they were an idea forced upon the writers by the producers.