I have numerous issues with Jennys death in Passion.
Let's first start with Jennys death itself. I feel it was well deserved. If Jenny had been more open and honest about her background and the curse put on Angel then Angelus would have never been let loose. In theory she is responsible for freeing Angelus, thus, brought her death upon herself. It is the whole Frankenstienian effect.
Second we can discuss the showing of her death. I have always thought it should not have been shown. You should leave her at the high school and nothing else is shown. The impact of seeing her dead body and understating the pain Giles felt would have been far greater. But by showing her death the fan was prepared and was, more or less, already grieving. To feel what Giles felt at the exact moment would have been far more powerful. The events of Jennys death could have easily been revealed in a flashback fashion when Giles confronts Angelus in the warehouse. Besides a bragging Angelus describing in a voice over the details of what he did and watching them onfold on the screen would have just been.. masterful.
Third, if you were going to show her die, have Angel do it. Joss originally wrote that Angelus kill her wearing his 'Angel' face but felt that would be too much for the fan to forgive, thus, Angelus killed her. I disagree, if it was Angel's face, the same Angel that people trusted and thought they understood, to see that face kill her would again have had a far bigger impact. You would know that not only was Buffy going to have to kill Angelus but Angel as well.