Worf's inclusion is what guaranteed I would start watching.
I don't even think Worf was written very well until later in his stay. In all his season four episodes he seems like a petty, dangerously impulsive manchild. They started to figure out how to write him better in season five.
The thing about Dax is, she had such an established personality it didn't really make sense to develop it anywhere. So she ended up being defined by her personal relationships and her comic relief.