What can I say? The immense popularity of Desu Nōto/Death Note is absolutely warranted. Its story is magnificent with twists and turns that leave you speechless, the geniuses on show are unprecedented, the characters themselves all felt real - each with their nuances, giving each individual a feel; by the end you can tell which character is which just by the things they'd say. The art style is great, and the story had good pacing, plot twist after plot twist yet it always surprises you... Death Note is a manga for the ages, absolutely great.
I recommend this manga for sure as you'd feel from my review (Yet it's no Nozoki Ana, that will always hold a special place in my heart).