This anime is mainly about a genius student Light Yagami vs a super detective L. The theme is about the Dualism, both want Justice in this world but with really different approach. You can expect easy to follow plot but with complex multiple stages of thinking from this anime. I also want to mention that this anime have one of the best soundtrack in anime.

p.s. It's my subjective opinion but I suggest you to stop after Light vs L battle is finished. Beyond that is different realm that really different than original Light vs L part.