She just wasn't Jadzia, but then she was never meant to be. The point of Ezri was that she was thrust into hosting Dax and had to really find herself, but given she only got one season (and given the millions of plots circling around her!) she never really had the chance to make her mark.
I liked her, though. And her relationship with both Bashir and Worf.
Truer words have never been said.