Don't worry, I grasped it, but it was done in such a mundane way it was fairly boring by the time she gained all knowledge and left her physical form. The film really didn't have a story beyond the drug lords and the drugs leaking and increasing her brain power. They tried with the scientists but it didn't really go anywhere. It was a real missed opportunity, but would have been much worse had she not been in the lead role.

It's similarities to Lawn Mower Man were in regard to a catalyst increasing their brain power to a point where they left their physical form and ascended into a higher plain of existence. Digital form for LMM and Accension into pure energy (photons?) in Lucy. Basically Ascension from Star Gate. Knowledge reached a point where you no longer needed a physical form. It was too limiting to remain.