This troper was introduced to Death Note by the live-action movies. Which she continues to consider as two of the best movies she has ever seen, with the complex interplay of the character's motivations, behaviour, schemes and counter-schemes, portrayed by excellent acting and script-writing. Very believable, with plans that were clever without being overly complicated, and amusing by turns.
So when informed of the existence of the manga, I tried to read it.
Key word being 'tried'.
It was too long-winded and grew too complicated, with contingency plans that would probably never work outside of fiction, and for a viewer/reader who had only seen the Adaptation Distillation
that elegantly kept the whole conflict between Light and L, the idea that L died and got replaced by two(!) successors was jarring. The main characters as portrayed in the manga were distinctly unsympathetic, all clearly out to satisfy their own egos with 'justice' as a convenient excuse/byproduct.
Movie!Light kept you guessing through the first movie, having you believe he really was just a Well Intentioned Extremist
- until the reveal about the true circumstances of Shiori's death. Movie!L seemed outwardly to be the same kind of high-functioning sociopath that Light was, but hints in his behaviour and dialogue leave you to draw your own conclusions about it. L's final scene was definitely simultaneously heartwarming and a tearjerker.
I didn't even bother with the anime.
I hear a lot of good things about both the manga and anime, though, and so I came to this conclusion: far from being different presentations of the same story, movie and manga use the same basic premise to tell very different stories.
You almost certainly will like one or the other. It's somewhat unlikely that you'll like both.