The horror/superhero movie has had an infamously troubled production, and its hopeful August release date is just the latest potential date for the movie. It's an offshoot of the X-Men series, focusing on five young mutants who are being held against their will and have to use their newfound (and poorly controlled) powers to get themselves to safety. Originally planned as the start of a trilogy, it's likely to be a standalone film, since the rights to the X-Men characters are now owned by Marvel Studios.
What to watch instead: The obvious choice would be the most recent incarnation of the X-Men, starting with X-Men: First Class. For a much goofier take on superpowered youngsters, though, Disney's Sky High is an underrated delight.