Gave it a 1 because it's got too many 10's. Seriously, this might be worth a 5, 6 or even 7, for some people it could be worth a 8... but 9 or 10? It's just a bunch of fans that are too blinded to actually evaluate this thing for what it is. For me, it's a 5, perhaps a 6. It's around average to slightly above average. It's not great(7), it's not amazing(8), it's not not unbelievably amazing(9) and it sure as hell isn't a flawless 10, for more reasons than I can remember.
It was somewhat interesting at first, but it quickly got boring, started to get into repetitive storytelling and got plagued with bad decisions regarding the plot, one such example would be killing off L and then starting over again with replacement characters, but there's many other things too, such as the book being possible to pass around. Then there's the character cast, none of which is particularly interesting or likable. Just take that light guy for example, he's hardly anything but a douche with mental issues and a general hate for the world, swinging his big d*ck(book) around and saying that he has a responsibility to cull everyone he doesn't find pleasing to the eye with petty excuses such as making the world a better place. Well, that sounds all well and good if we exclude the part about him trying to make the ideal world FOR HIMSELF, meaning that anyone who doesn't agree with his views would be fcked, kinda like when you have an argument with someone over the internet and yell at each other a bit for differing opinions, both gets aggravated and annoyed, but this guy would kill you because you didn't agree with him. He's pretty much a child throwing a tantrum about life and how horrible the world is to him, only that this guy has a cheat that can kill everyone he looks at and writes down. Boring, really.
Well, there's a lot more that I can mention, but I don't care to spend more time on this. In my opinion you shouldn't read this manga if you've read a lot of novels+manga and watched a lot of anime before. Stuff like this tends to be great when you're newer to it all, just like generic crap such as bleach, dragon ball, one piece, naruto etc, you get my drift. When you're deep into this and has read thousands of manga+novels and watched a few hundred different anime, or at least a hundred or so, it's probably not going to be a good experience. This is not a great work, but I guess it could be a fairly good introduction to the somewhat darker side of manga/anime/novels. It tends to be nice to start out simple. Just keep in mind that few to none characters in this manga is likable and one of the least likable characters is the one introduced at the start as a mc, that light guy who got the death note. I do, however, applaud the creators for the "Just as planned" face that we tend to see here and there in other manga. The L sitting posture is also pretty nice.