Personally I'm in the latter camp. I really only liked her character the first time she showed up, in "Indiscretion".
It also didn't help that they had the character played by three different actresses; I still don't know why that was necessary. For me, Cyia Batten, the first actress to take on the role, and who only played her in I think two episodes, was the only one who could make Ziyal anything near likeable.
She gave her the kind of artless innocence that the writers seemed to be going for, and which in my opinion the other two didn't pull off, making her come across as naive and annoying instead.
I don't believe the character worked well overall, mainly because I find it impossible to follow why a man so consumed by ambition, and furthermore a man with seven legal offspring, should be prepared to lose his standing and reputation and have his family disown him all for the sake of one illigitimate Bajoran half-breed. And that given he was prepared to kill her in order not to risk those very things.
Also I have no idea what she was doing on the freighter and certainly not on the damn station during a war! She should just have been packed off to safety in the Federation somewhere...
Basically I shared Damar's opinion of her in just about every respect and I cheered when he executed her.
(I can see I'll be making friends among Ziyal fans here...)