The introduction of Worf shook things up a bit, but he fits the show very well and he already has good chemistry with the rest of the cast. He didn't dominate the series the same way Seven did when she was introduced on Voyager, but he did get some additional screen time to facilitate the adjustment.
Definitely agree with this, and I'm one of those that was lured over to DS9 from TNG because of Worf. When Seven came to VOY it became the Seven show. When Worf came to DS9, he fit in quite well on the Island of Misfits Officers. And to me "fitting in" doesn't mean he became everyone's BFF, but that his character worked well. I wish they had done more Worf and Odo, cause I really liked their "I don't like you even though we have a ton in common" dynamic.
But, by definition, by adding one more character but not adding anymore episodes to the season means that there's less screen time to go around. Ironically, I think it's Dax's characted who will suffer the most from Worf's introduction. When it initially happened way back when I figured Kira would be the one to lose out with their roles on the station being so similar (cause, essentially, Sisko has two first officers now) but Dax kind of loses her place as the "resident Klingon" when he comes aboard and end ups being nothing more than his sidekick for the rest of her time on the station.
(Not that any of this is necessarily a bad thing, I think she was probably the weakest regular character anyway)