Death Note is one of the most powerful anime I have ever seen. The story and thought behind it are amazing at every turn. You have to keep up and pay attention, but if you do, this anime will give you immense satisfaction.
Right up until episode 25. I have watched the entire thing, and with that in mind I can reccommend everyone to stop watching after that episode. That's where shit really goes down the drain. My score is based on the first 25 episodes. If I had to judge them all, the overall score would go down to 7 or 8 because of this last story arc.
In any case, I do strongly reccommend everyone to watch it, it's amazing.