For those, like me, that enjoy reading descriptive reviews (which are usually the bad reviews) more than just "this is great", here is a descriptive review. {Important to note that I haven't read the manga.}
First time I saw the movie I didn't quite get everything so fast. It felt like something was already in motion and this is just an episode of a bigger series. So yes, it might be a little confusing at first.
Although, if you pay attention and continue to absorb what is presented to you, the movie continuously tells you what is going on, giving you a hint about the background (that being "what happened to society and humans?", "why the characters are trapped?", "why some machines and the system are against humans?") it is just a more smart and deductive process rather than doing what most animes do, telling you upfront everything.
It is a sci-fi anime and has a very immersive atmosphere it reminded me of games like metro 2033 and stolen. It has a protagonist, but he is silent most of the time (like Master Chief in halo or other protagonists that interact very little, taking action silently). The interaction between characters is very interesting and way more realistic than in other animes.
It is an extremely high-quality anime, with a complex/deductible story, and realistic characters in a dystopic future controlled by machines. It is smart and dark. If that is your thing, then you should 100% watch it.
[This genre reminded me of Knights of Sidonia and somewhat psychopass]
Note: don't let people fool you. There is no "this anime is a waste of time". Every story is a story. Some are well produced and some are not. If you don't like smart movies then do go trash talking about them. Just go watch something with a simpler plot. Evaluating as a show, this is 5 stars for me. Worth watching.