Watch the trailer instead of the movie. It will save you about 87 minutes.
It could be described as a cross between Limitless and Akira but not equal to either of those superior films. Scarlett Johansson makes a good effort, especially in the beginning, during the short time she is still human, but the material doesn't give her much to work with. The story suffers from the problem of going too far too quickly in the first act so that what follows is almost meaningless. This could be forgiven if the action sequences where fresh or spectacular but they offer nothing new or compelling. The action quickly becomes like shooting rubber bands at Superman. There is no danger of anyone getting hurt and we wouldn't care if they did. Lucy doesn't live up to the legacy of fine films from director Luc Besson. There are some tired car chases and gun fights. He retreads over familiar action territory reprising scenes that are remarkably similar to those in The Professional, but not as good, down to a rocket being fired down a long hallway. Skip this one and watch The Professional, La Femme Nikita, or The Fifth Element, in that order. Perhaps if you have already seen all of these other films and Lucy is available through Netflix or cable it will make for a lite diversion but don't waste your time in the movie theater for this one. You've been warned.
Rent it only if you are truly starved for entertainment.
Lucy is rated R for violence, disturbing images, and sexuality.