The premise of folks never aging past 25 years, but needing to add more time to keep living is intriguing, but the execution of this movie is flawed. The science questions are glossed over to focus on a Bonnie and Clyde storyline with Timberlake and Seyfried. Much of the movie is predictable and quite a bit of it makes no sense. It's the future, but people still use payphones? You can't even find a payphone these days.
All the adults are supposed to be 25, but they're all a very hard 25.
I do not recommend this movie. It doesn't mean you shouldn't watch it, but you shouldn't expect much from it.