I've seen that (..of course!), and it's not a bad effort.
Helps a lot if you like John Cusack, and can easily imagine him as a sci-fi writer.
If I remember right, the film's ambiguity about the 'Martian' boy does not survive past a mawkish ending. Not read DG's original story, but I assumed the film's non-SF ending was in keeping with that..?