I don't know why people give this anime so much hate. One of the most common comments is "the first 8 episodes are boring, it needs more action", I don't think it does. This is not a shonen, it's a thriller, so the slow pace actually helps the overall story and builds up the tension needed for the plot twists that come after episode 9.
Also, the plot holes. It does have some, but not as many as some of the reviews depict. If you pay enough attention, everything is intertwined. I also see people complaining about the lack of explanation on the significance of the dolls. [SPOILERS AHEAD] Aside from Mei's eye thing, it's a diversion tactic, which is pretty common in thrillers. Not everything must be related to the plot, sometimes it's there to make you form theories in your head just to knock them down with a plot twist a few episodes later.
Overall, this is a well done anime. From the flawless animation and character design, to the soundtrack, to the storyelling and the plot itself.