The story is quite ok. Well, I don't really like the main idea of the survival game and all but I admit that most of the shocking or at times disgusting events are necessary for the character development. What makes the plot actually pretty great are the several twists and the unpredictability of the storyline. Whatever you think, you can be sure that the anime won't fail to surprise you. Also, the idea of the future diaries brings with it that you can expect some ingenious tactical moves. (Sorry for comparing again but I couldn't help to mention Death Note and Code Geass at this point. While they are mainly based on strategies, Mirai Nikki is more like a perfect mix between genres, including the one with a genius MC with supernatural abilities.)
The MC, Yukiteru seems most of the time a little pathetic but he is the most realistic character in the whole story, so you can say it's quite normal that he just won't act like a badass. Yuno's character development, on the other hand, is really exciting to watch. Most of the characters are really well-made. Most of their deaths or their situations at the end of the anime turn out to be a satisfying alternative. This is what keeps this anime from sliding into the ultimate thriller genre and what makes it enjoyable also for people who like the shounen-type stories more.
So overall I would rate it 9. Because once you start watching it, you'll just have to finish it.
