I thought this was a great movie. The premise of the movie (cyber attack destroying the Internet) is frightening in itself even if it is very unlikely. Nonetheless you can imagine the devastation if there was no Internet, Wi-Fi, GPS, or infrastructure operational. More plausible than many other apocalyptic movies. Kept your attention and on the edge of your seat throughout. If you like a apocalyptic movies you won't be disappointed.
Bear in mind that many of these negative reviews are motivated by dislike of coproducer former president Obama. Many of those reviews are biased because of their dislike of him.