Kiseijû

I'm personally an anime watcher of Parasyte, so I obviously don't know about the greatness of the manga, just a disclaimer. I personally found the gore of this movie to be extremely unsettling, it's not even censored like the anime and they even try hard to feed you as much gore as possible, making the series 80% darker than it is presented in the anime. As an anime watcher, I felt uncomfortable by the way they shifted the scenes around and certain changes, but I guess it is necessary to do so to fit as much as they can into the movie. My friend who has yet to dive into this series found the story plot good, so I guess it can pass as a smooth story plot for a movie. Finally, I must really praise the CGI and sound effects used, simply spectacular. In my opinion, I would recommend watching the anime series as there is more time for slower and steadier character development, especially for Shinichi, the main character, that we can appreciate, and the gore factor is not above the roof; but just watch it and experience it for yourself. :)