Lucy is pretty thoroughly rotten. It makes a complete hash of it's central idea, presumably so it can get on with being a dumb action movie. And then forgets to be a dumb action movie.
Even ignoring the hacky brain capacity device it uses the movie doesn't have much to say of interest.
Ramping up Johansson's power levels so quickly that there is no tension in the film, the 'action' beats basically have her switching people off. At one point it looks like it is going to set up a bad guy to ingest the same drug as her to give her someone to fight but he just puts them in a briefcase and walks into a corridor. thrilling.
It attempts a 2001 riff it's climax which is much much sillier than Interstellar's (and that's saying something) and lacks any of it's grand visual sense.