The very first anime I've ever watched, the anime that dragged me into the otaku society. Definitely not overrated; Death Note deserves it's popularity, hands down.
The first few episodes deserve an absolute 10. The storyline can be described as horrific and humorous at the same time, with a tad bit of romance in the later episodes. There are only a few scenes that involve actual fighting, though that's not a downside. The main fighting method among the characters are almost always a battle of wit, unlike most other animes. Each episode leaves you in the extreme cliffhanger. BUT, I believe the second season should have just ended the whole series somewhere there.
MADHOUSE is well-known for having great plots and great animation. Death Note is no exception. The dark imagery makes this show's animation.. flawless, in its own way. There are those scenes between Light and L where everything just explodes into blue and red, and that just blends into the suspense.
Although I don't really fancy in the opening and/or ending themes, I do love the sounds of the actual show. The voice actors are perfect for each character (in both the sub and the dub), and the background music can often cause a lot of suspense.
Death Note has a bunch of interesting characters. In the first season, most of the characters show their personalities very vividly, except for the two main ones, Light and L. If it weren't for their narrations, they'd be complete mysteries to the viewers.
Then there's Ryuk, the Shinigami. You could say he's the guy that made everything in the Death Note world happen. You see, he was 'bored' one day, and happened to 'drop' his book into the Human World. This leads to the mass murder of malefactors. As the series progresses, he turns out to be more of a comic relief. He's got this obsession with apples, and.. well, you gotta watch it to understand. He has the same expression on his face every time, which is great for those serious-funny moments.
I think the second season had quite a bunch of unneeded characters, though. They did serve their purposes, but I don't think the viewers care much about the development of the minor characters.
I was really impressed with this show. I had low expectations of anime before I watched it, and this series just really left an impact on me. I wouldn't agree with it being 'the greatest of all time', but I would agree that it's a must-watch for anime lovers.