Some good fight scenes and visual effects makes the movie entertaining to watch.
A lot of philosophical ideas are presented in a way that are fun to think about and are displayed in visually interesting way.
Although some applications of Lucy's perfected mind fall flat, some are very interesting.
They cast a mediocre actress (who is usually only cast for her body) and had her speak in a monotone voice for the whole movie (and not showcase her body). If you are selling sex, sure, go with Scarlett Johansson. If you are selling a character that becomes so complex she evolves into something beyond comprehension and human relation, go with... anyone else.
In this interpretation of a woman that evolves past her humanity, she becomes an emotionless and purely logical being. However, the movie tries so hard to be stylistically artsy. There are constant jump-cuts of primal creatures and flashes of text, which to be honest, don't even really work within their own right, let alone in the context of the pragmatic Lucy.
The drug itself is probably the most important piece of the story beyond the story, but it goes totally unaddressed. Who makes it? How? Why hasn't this happened before? What's to stop it from happening again? These are questions that are of more consequence than the ones addressed in the movie.
When you have godlike powers, and people on your side die, that's your fault, not the villain's.