Great ideas and plot twist, but disappointing

Rating: 7/10 (17 January 2020)

This movie is very well done. From early while watching it, I felt that maybe Caleb was being deceived. I thought that maybe Nathan had created the context for him to sympathise with Ava, and the blackouts were created by him to make Caleb feel more immersed as he'd think he was talking in private with her. I was astonished as the matter was brought up by Caleb!
It was also nice as Caleb questioned Nathan, the reason why she was female, if she was being sweet and seductive to him as a way to increase the empathy and the feeling she was alive, and how Nathan questioned back if she was indeed interested in him or deceiving it.
Even when she told Caleb to not trust Nathan, I considered he programmed her to do so, to create even more intimacy. Maybe the real test was if Ava would be able to make Caleb fall in love for her, and not just feel she's alive. Having her locked up and the feeling of a hidden plot would be made up, to make him believe she was in danger and that he needed to save her.
Sadly, the movie moved into a dark and unrealistic direction. Nathan had no reason to keep his robots locked in a room, even more when he's on a private island. If they'd be seen, it'd be easy to say they were his employees. Indeed, I missed the part he said Kyoko was a japanese servant that didn't know english and noticed from beginning she was a robot.
If a robot would fret wanting to leave, he could just disable it and reprogram it to not act like that. He'd not be out of control of their decisions and desires like that, and would never let them break themselves. And, if at some point anything went out of control, he'd add measures to not let it happen again, in example remotely turn off a robot. When Ava left the room, he'd not need to fight her, he'd just shut her off remotely.
I understand that Ava letting Caleb locked was a point script writer wanted to make, that she wasn't in love or interested on him, that she was indeed deceiving him when flirting and seducing, to make him deeply wanna help her, and show her with a psychopath personality. That's interesting, because psychopaths are able to understand and express feelings, but they are unable to actually feel them. That fits perfectly on an AI, that learns to understand and express emotions, even the most complex ones, but remains unable to feel them.
Still, I think that if she's that way, she'd either kill Caleb so he couldn't take an opportunity to stop her (maybe, when he'd see she killed Nathan, he'd see her as a threat and rethink releasing her), or keep lying and flee with him so he'd keep helping and protecting her.
In any way, Ex Machina is a fair above the average movie, certainly worth watching a few times, and brought up some very interesting themes to the automated AI philosophy.