Sorry, I can't write this without spoilers. I'm only ruining about half of the first episode, anyways. If you want the version without spoilers, here it is: AnoHana is about a group of friends who have lost touch over the years, and are brought together by a reunion with someone who knew them back when they were all close. Complex relationships, drama, and occasional cuteness to be had. Now, if you're not looking for spoilers, run why you still can!
Story: AnoHana starts off as being about a guy who believes he's hallucinating a vision of one of his close friends who died when he was around six years old. Back then, he was the 'leader' of a large group of friends who spent their time playing and hanging around in a clubhouse.
He realizes she's not a hallucination but is in fact, a ghost (she knows things only the real her would have known), and sets out to grant her wish so that she can move on and rest in peace. Her main wish seems to be that the group of friends become close again, despite a decade of separation and growing apart.
Throughout it, the feelings that each of them had for their dead friend surface. Some of them were a little too fond of her, while others secretly had a grudge against her. Likewise, the day of her death also surfaces — most of them have reasons for feeling guilty, because in their minds, if everything hadn't happened a certain way, she wouldn't have died.
Which is true, but in the case of all such stories, it 's not like they could have known or prevented it.
If you can't tell from the story's description, it has a huge dramatic, tearful wrap-up. All of their problems get pushed out into the open, and they leave the show friends once more, while still moving forward as the individual they had become over the past ten years.
Animation: This show doesn't have any stunning glowing magical visuals or smooth action sequences, seeing as how it's set in the real world. Meiko, the ghost girl, doesn't look like a ghost until near the end, so you can't even go by that. What you can go by, however, is the fact that their surroundings are gorgeous, and the characters are well drawn. The animation is relatively smooth and clean.
Characters: The characters is where most say that the show fails, namely the characterization of Meiko and the fact that all of the teenagers are reacting to her death as if it just happened, not as if it had happened when they were small. I'm going to defend the show a bit here.
Meiko — yes, there was a failure here, but not in her characterization. She's sweet and selflish, naive and just wants to play with her friends. She has little character development, especially compared to the other characters. However, the failing here isn't her personality. The failing is that the aged her up as a ghost. If she'd appeared as a five-year-old ghost girl, her being so ditzy and naive would have been attributed to her age, especially considering when she died. However, the anime chose to age her to a teenager. While still somewhat loli-riffic in that she has no breasts, the anime obviously made this choice so that the main males wouldn't look like pedophiles for 'liking her like they want her to be their wife kind of like.' She does have some character development in that she makes the transition from wanting to stay with her friends to wanting to move on and be reincarnated, and she also moved on from not wanting to bring up feelings of romance (once again, keep in mind she died at five or six or so) to admitting she liked the main character in that way.
Another 'failing' people bring up is that everyone reacts to the death as if it's been traumatizing them for the whole decade, as if they hadn't moved on from the fact. But that's... almost believable as well, if you look at where the characters were when the anime started.
If I go into detail here, well. I'll just ruin the whole anime, won't I? But most of the characters were either friendless or for various mostly-plausible reasons, could not let the death of their friend go. The other two females of the group, Anaru and Tsuruko had basically moved on when Jintan made it all come rushing back by bringing her up. Well, the rushing back thing as well as realizing that they each had a crush that would probably never become a romantic relationship.
Anyways, the characters are interesting and watching them interact with each other despite completely different personalities is enjoyable, especially considering how most of them haven't actually spoken for many years.
Overall: Overall, I enjoyed the show. It was light-hearted in the right places, and the ending did make me cry, which is a somewhat uncommon thing. I think the only other animes that ever made me cry were perhaps Air and Kimi ga Nozomu Eien, proving that I shouldn't watch dramas set in the real world, or I will bawl.
I'd recommend the show to anyone that doesn't mind stories of grieving or overall 'sad' themes and who doesn't seem to be too critical of the 'airhead' character, which is common in anime nowadays but is started to become a hated cliche by most... I still don't mind them, even if they pop up in nearly every anime, but well, others are getting ready to stab them through the face with a ballpoint.
I digress. Again. Overall, I think it's deserving of its high ranking, and is worth watching.