I personally liked this one. I'm guessing the hate for it is... well, I don't understand it, honestly. it's not the most coherent story ever; this is the epitome of style-first, like one of those action movies that doesn't pretend to be about deep plotlines.
anyway, what I'm trying to say is that I have a strong fondness for it. great character aesthetic, and I think the anime generally did that justice. my main complaint is not "overrated! bad plot!" at all, but rather that it feels unnecessarily cruel at times to its characters, and I found myself rooting for several of the other diary-holders at times. I did think it was gripping though; it earns all its genre tags and then some.