I didn't like this film and I am glad that I rented it only instead of buying. Below, more of my impressions, with some limited SPOILERS.
In 1979 a group of young teenagers is working on an amateur horror film about a zombie infestation. One night they slip out of homes to film a scene which happens on an abandoned railway station. When doing it they witness a terrible train derailment, during which SOMETHING escapes from a kind of an armored wagon... and then the film really begins.
Even if this film was directed by J.J. Abrams (which made me suddenly very concerned about the next STAR WARS movie...), it was produced by Steven Spielberg and it is clear from the beginning that "Super 8" is just a mixture of recycled elements from "E.T.", "Close encounters of the third kind" and "Taken" TV series. It wouldn't be a problem if this mix was well made - but it was NOT!
The story is silly and terribly predictable, filled with every possible cliché in the book. US military and US government are presented as some kind of Nazis. The alien creature is a kind and gentle thing and it kills only bad people, namely those who wear uniforms... A drug using, vulgar slacker (Jeez, what a role model!) is the main ally of children against the bad US government, who not only abuses gentle alien creatures but also routinely murders US citizens. I also couldn't really feel any sympathy for little heroes from "Super 8" - unlike in "E.T.", far from being nice kids, they are a mixture of boring and annoying brats with deep issues.
As many other recent films, this one tries to be a sci-fi film for both adult and young public - just to fail on both counts, as it is too violent and scary for a kid's movie and too childish for a grown-up movie...
I hardly managed to finish watching it and at the end I was simply relieved that this ordeal was over. Avoid!