The story does have a strong NGNL feel to it, but it also feels rather rushed and as if it wasted quite some potential. The movie may go for almost 2 hours, but you see almost nothing of all the other races. You see flashes and glances of some of them, but nothing really concrete, and even those glances are usually not for very long. The real focus of this movie lies on humanity's struggle for survival... and for what it's worth, what is shown is pretty enjoyable for the most part.
Simply stunning. As usual, NGNL is a feast to the eyes. It has the usual artstyle you'd expect from NGNL - as seen in the series as well - and while I could understand if some of this style may not be your thing, I promise you that you'll still enjoy other parts of the art. It does use a bit of a darker tones for some scenes compared to the original series, but it's still the same style overall.
As with the art, the sound is great as well. The sound effects have amazing impact, and the music makes you feel more strongly along with most of the scenes. I can't really think of any suggestions to improve this.
Like the story, the characters feel rather rushed. They practically just pop into being, and are barely explained. Their character developments also feel like they speed from one step to the next just a bit too fast. The main characters even look like exact copies of the main characters from the NGNL series, which isn't really that believable and makes them feel more like them instead of their own separate selves. While the characters aren't horrible overall, I would have preferred more attention spent on them.
The art and the sound are the main spectacles here. This doesn't mean the rest is bad though, just not as amazing as you might expect. I also have a personal gripe with one of the aspects of the story, though telling that would be a spoiler. Overall, the movie was a good watch, but that aspect of the story as well as the rushed story and characters left kind of a bitter aftertaste for me. That's why I'm giving No Game No Life Zero a 7 out of 10: enjoyable, but leaving a bit to be desired afterwards.