The only reason why this movie was made was to ride on the success of the previous 2 movies and rake in some cash. So all the writers did, was to use the same story, put in a new villain, 1 or 2 more characters, and a hell lot of action and expected the film to repeat the success story of the previous Terminator movies. But sadly it falls well short of expectations.
The basic flaw is the story, which is the same as the previous movies - send back a robot to ensure that John Conner, ’the last and best hope of mankind’ lives. Nothing new apart from the all-new cast, who again are nothing exceptional.
From a scientific point of view the film in full of inconsistencies. What’s the point in sending a robot back in time to save a person who is already dead in the future?? Even ’the rise of the machines’ part is not fully explained - at one point everything is going on well with humans in charge and the other moment the Skynet AI takes over, without even pausing to tell us what the Skynet is all about. The director seems more interested in showing the audience the action sequences rather than telling a coherent story.
If you want to leave your brains out and are only interested in action then you may like the movie. But if you expect an interesting plot interspersed with cool action then I’d recommend you stay away.