I actually really like Ezri. She was fun and upbeat and had a dynamic that was different than the rest of the crew. On the other hand, I completely understand the complaints. It wasn't really Ezri that was bad, but that the writers were so excited to have a new character to play with that she got a disproportionate amount of screentime. In universe there are problems too. Trill re-associating with old flames was such a big deal, there was entire episode about how closely two of them were being watched, even though several lifetimes had passed. Ezri showed up at her old workplace and started fraternizing with her prior husband and a coworker she'd known even longer, but not much was brought up about it. It also brought back the Bashir/Quark loves Dax plotline which I think was best left alone.
Still a better addition than Vic tho.