ART: The art is amazing. It has a realistic feel to it, and the details of everything (hair, clothes, backgrounds) are just amazing. However, sometimes Obata tries to make a scene funny by going into a more chibi-like style, which ends up looking strange and out-of-place in the manga's serious tones.
CHARACTERS: The main characters are VERY fleshed out, and their thoughts are documented so well that you can be stuck between siding with L or Light about who is in the right. The problems with characterisation only pops up with the minor characters: they have little, if any, personality traits to make them very unique. Sure, you can get a few ideas, but when compared to the strong, over-shadowing personalities of the main characters, they fall a little flat. This unbalance sometimes hinders the ability to identify with the situation, but it's a bit understandable when you remember that these characters are BACKGROUND characters.
PLOT: The plot is simply jaw-dropping. It is full of suspense and psychological evaluation, making the manga a page-turner if I've ever seen one. The undertones of morality and the meaning of justice further draw the reader in, especially when the cat-and-mouse (well, it's more of a cat-and-cat) game begins between Light and L. Unfortunately, however, the plot begins to die around the seventh volume. While the suspense remains, it loses the spark it had in the beginning, and even the most suspenseful volume (the last, of course) lacks the realism portrayed in the manga's beginning. If the plot hadn't dropped out in the middle, I am sure that I would've given this series a full 10/10.
This series had amazing potential, but little inconsistencies and issues slowly destroyed its chance at perfection. Even so, it is a rare find in the world of manga, and I highly suggest anyone to read it.