This episode could have had potential if only the plot wouldn't be so dumb.
So, another Ezri episode and another murder mystery - not long after she already had a character episode and a murder to solve. This time, random people are murdered on DS9 and who else but Ezri could lead the investigation. A former Dax host was a murderer, so if only she can use his memories, she should be able to find the murderer - because she then thinks like a murderer.
Something interesting could have evolved here. Jadzia and Curzon always ignored the thoughts of the murderer deep within their minds. Unfortunately what comes next is not interesting. It is dumb.
First, the interaction with the memories of her former host are presented as if this dude would stand next to her and guide her through the case.
And second, the conclusion is as stupid as it gets. Ezri finds out that all murdered people have a photo from them in their quarters on which they are smiling. And of course the murderer then can only be a Vulcan, because they dislike emotions. And of course this one Vulcan murderer is in the same elevator as Ezri and her former host directly points him out to be the murderer. It is really that dumb.
And again: This Ezri character and the actress are just not interesting at all. She is just an insecure child that talks too much.