Entertaining in a way, but a little silly and flawed. Whilst Scarlet Johannssen may well be establishing herself as a bit of a Sci-Fi goto-girl, and her performances are always excellent, the premise and story of Lucy are unexciting and not grounded in science past, future or fantasy.
Even if there were such extreme potentials of the brain waiting to be untapped, the ability to type at the speed of blur on dual laptops simultaneously seems a nonsense. But the ability to deconstruct your own anatomy and turn into a black, amorphous blob simply ludicrous.
Maybe I just prefer my sci-fi to be constrained somewhere within what I consider to be the realms of possibility however fantastical that may seem.
Having said that, it entertained me and I managed to stay awake (the acid test), although seeing Morgan Freeman in every other film I watch is starting to trigger ever increasing narcolepsy.