The film is namely to a future in which there are operating systems that communicate, learn and even develop emotions independently with one. This in turn can inevitably lead to social conflict, we feel partly already by our smartphones, tablets etc. Thank goodness we are not yet as far as in the movie, but if that were so, it already would have to ask what makes a people respectively each individual human and what is actually artificial.
That is why "Her" also created quite philosophically, even though the strip is actually a complete love story, but without pathos or honey delicacy. Actor Joaquin Phoenix plays almost all on the wall and it's surprising how you can get it no Oscar nomination for the lead role. Regardless stings Scarlett Johansson in the film extremely apparent, although you can hear throughout the film only. What the woman with her voice (especially in the original sound, but Luise Helm in the German dubbing is just indescribably good) is cause for emotions not only crass but also scary, sexy, unexpected and somewhat bizarre.
However, "Her" is a very quiet, deeply moving film, where you have to devote time and should also indulge in a bit. For the viewer gets an inside withdrawing story when one is stimulated at the end for discussion and reflection ... great recommendation for film buffs and want to be there.