Raito (or Light) is an ordinary college student, top of the class. Until one day he finds a notebook (Death Note) with some very peculiar rules written into it. If you write someone's name into the Death Note, they will die within 40 seconds. As he watches the news, he see something is going on, writes down the name of the criminal and dies within 40 seconds of a heart attack.
This encourages Raito to experiment further with the notebook, and he also meets the owner of the notebook: Ryuk. Ryuuk is a Shinigami (Death God) and is now bound to Raito until he dies or relinquishes ownership. Considering criminals are dying all over the world, this attracts attention from the police. The police force in Japan calls in the help of L. L is a super detective and with the help of the police they're trying to catch this killer, or Kira. Did I also mention that the Chief of the police task force is Raito's father?
I've read the manga and seen part of the anime. The manga and anime differ from each other and so does the live action movie. There is a lot of background you'll miss from the movie, but it's not needed. There was a second movie, which I'll review in a minute
Now the movie basically describes the first quarter of the manga. You see how Raito gets the book, how he experiments with it and his philosophy. He basically wants to create an eden, where there is no crime and he will be a god. The more you watch, the more you think he's right. Crime does die down, people are scared of Kira, because he can judge them.
On the opposite spectrum, you've got L. He's a quirky young man, and when I say quirky, I DO mean quirky. But he is highly intelligent and tries to find out who this Kira is. There is a constant dynamic between Kira and Raito.
Do not expect a big action movie, expect a battle of wits. There will be deaths, a lot of them, but not in the hack-and-slash variety. You'll be rooting for Kira/Raito, but as well for L.
Overall, i give this a 5/6. Mainly because i'm a fan of the manga and follows it closely and yet brings something new and unexpected to it as well.