Pretty terrible, as I guess can be expected when it comes to M. Night movies now. There really is very little to the movie.
Father and son still grieving over the death of the daughter/sister crash land on a "class one quarantined planet" (Earth) where the animals have supposedly evolved to kill humans. The dad is badly injured in the crash and will spend the remainder of the time sitting at the computer console monitoring via camera as his son traverses from their crash to where the other part of their ship wreckage fell in order to retrieve and then fire the distress beacon. Son must evade and sometimes do battle with the indigenous creatures of the planet along with properly monitor his oxygen levels and body temp as we're told that the planet becomes exceedingly cold each night to the point that unless he is able to reach "hot spots" before nightfall will kill him.
That's pretty much it and Will Smith does practically nothing for the bulk of the film, a problem when he's the reason most people would even go and see this movie, especially since we got a similar film a little over a month ago in Oblivion except that film actually had more to its plot. Not helping matters is a very lackluster lead performance by Smith the Younger. He's whiny and never once shows any of the charisma that made Daddy Smith such a big star. In a summer with no shortage of sci-fi on offer, there's really no reason to even consider seeing After Earth.