Hello, finally managed to watch! and read all your comments. SO much to say. Overall I enjoyed it. I found it a bit disjointed in terms of plotlines unfolding - I felt they were setting it up to be some drawn out mind game, and then PS just capitulated and confessed to Stella. I enjoyed their interview v much, just felt it didn't fit with what came before.
I still LOATHE the Benedetto girl character 
- and agree with pp that her storyline seemed ultimately to have no significance. I think her character was totally ill conceived and the performance was weak (why must she ALWAYS smile when she talks?!!). There's no way that the interview with Merlin wouldn't have scared the shit out of a 16 year old, unless they were a psychopath, and they leaned so heavily on her being infatuated or thinking it was some sort of game...the transition just was not convincing. Her blonde friend was also not horrified enough by the prospect of a serial killer 
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And would she have been out at home before her / Spector's trial??
What I enjoyed most was the explicit exploration / discussion of male violence - Gibson's conversation with Burns, and her response to Merlin in bed. I believe her when she says that she loathes Spector. I don't assume that her fascination with him has collapsed into something sexual - in the interview and her conversations afterwards she not only seems perfectly in control, but also unimpressed by his sexual aberrance, which she finds ordinary... I don't think she's guilty of the same. I think her horror at the end can be born of a non sexual obsession, her obsession with the job, the fight, her hatred of misogynists. What Spector said about letting men perish rang true and I liked that the writers didn't have her deny it, nor did they soften the portrayal of men, which was pretty unforgiving. My reading of the Olivia scene was just that Gibson found it abhorrent that he be afforded such a privilege (of lying to his daughter) when he's been running around strangling other people's children.
I enjoyed her dismissal of Sally Ann a great deal
But am uneasy, like other posters, with the overall portrayal of women.
I also liked DCI whatsit's smirk at her turning up with Merlin. In fact I liked him as a character overall. Nice to see so many men working for a woman with no apparent problem with it.
I didn't like McNally being dressed up that way, it felt voyeuristic (not sure if this is quite what I mean), not to mention painfully obvious, and beneath Stella, who would/should have had more respect for McNally.
Oof sorry. Just SO much to say! and noone in RL to discuss with.