DS9 did not improve after Worf's arrival.
In a way, it became worse because it wasted a Season on a pointless Klingon War that went nowhere instead of focusing on the Dominion, which would have been much better.
DS9 improved as of the Season 2 finale, when the showrunners decided to ditch Bajoran politics (for the most part) and instead focus on the Dominion. In other words, the improvement of the show had already happened way before Worf arrived in Season 4.
Like the Dax characters, Worf does not really fulfill any necessary function on the show. None of them have any legitimate reason to be included in the cast. Unlike the Dax characters, however, Worf is not inherently annoying and grating to watch/listen to.
So other than sidetracking Season 4, the addition of Worf had no effect-good or bad-on DS9.
In a way, it became worse because it wasted a Season on a pointless Klingon War that went nowhere instead of focusing on the Dominion, which would have been much better.
DS9 improved as of the Season 2 finale, when the showrunners decided to ditch Bajoran politics (for the most part) and instead focus on the Dominion. In other words, the improvement of the show had already happened way before Worf arrived in Season 4.
Like the Dax characters, Worf does not really fulfill any necessary function on the show. None of them have any legitimate reason to be included in the cast. Unlike the Dax characters, however, Worf is not inherently annoying and grating to watch/listen to.
So other than sidetracking Season 4, the addition of Worf had no effect-good or bad-on DS9.