Story: If I had to give rating for the first arc, it would be a 10. If I had to give a rating for the second arc, it would be about an 8.5. If I had to give a rating to the 3rd arc, it would be about a 4. Death note started out really great but towards the end it killed it. The third arcs characters and story line fell flat especially compared to the first half. The ending was not fitting at all (I preferred the manga's ending). Also, although the second arc was still great, it somewhat copied the first arc. All in all, Death Note's story had so much potential and didn't quite come through all the way. However, I still liked it and would recommend this to most people especially those who like psychological thrillers and those who like animes that make you think. Also, the long monologues that explain the character's action aren't superfluous. I consider myself a pretty intelligent person but when it comes to why a character did what they did, it's beyond me. With no through explanation, I would definitely be lost.
Animation: Holy smokes is the animation amazing. The colors are bold unless they have to and that fits. The first opening was amazing unlike the second which, personally, failed. The expressions fit perfectly and the character designs are memorable and interesting. The shinigami world is creepy and dark and, interestingly, has the same feel as the human world. Movements are fluid and, as a whole, the animation is engaging.
Sound: Like the animation, the sound is amazing. The voice actors fit their roles both in the original and the English. The soundtrack is memorable and fitting. The first opening and ending are fitting unlike the second opening ending (this maybe personal preference because I don't like screamo). I would definitely buy the soundtrack to this.
Characters: Light is a real bastard. I know he's supposed to be an antihero but you really want to see him get screwed over. L is incredibly lovable and endearing especially when he's being politically incorrect. Misa is annoying and Ryuk is awesome. The first half of series produces amazing and memorable characters. However, the second half lacks in good characters and character development. Mello is one of the few ones where you actually see development.
Overall: In all honesty, Death Note has way too much hype. It does have depth and the animation and sound are phenomenal, but that can't make up for the second half of the series (I'm not just saying this because I love L). However, I would still recommend this to people but with the warning that it goes downhill after twenty something episodes.