I watched a series of mini-movies/episodes called Kara no Kyoukai' (Boundary of Empiness) about a year ago now, which surprisingly is like the only anime I've truly thought was 'great' in a pure sense of the word.
The story does have weaknesses, the pseudo-philosophical concepts it tries to put across translate to English quite badly, which makes some dialogue too wordy and jargon-ish. But on the positive side, it makes the plot and story concepts incredibly unique and unlike anything I've ever seen or read in fiction ever.
The characters are also amazingly well-done, which almost none (except perhaps the protagonist's sister Azaka) falling into cliches or stereotypes like in most anime. The interactions between characters are also very good.
Also, the series is pure genre-killer, it's not mystery, it's not horror, it's not romance, it's not supernatural, it's not fantasy, and it's NOT a hybrid of all of them, it's all of them at the same time, in a contemporary real-world setting. You cannot nail down the genre of the series as anything but completely unique.
If my word means anything, which it probably shouldn't, watch this series, it has an English translation and all. Also the novels which the series was based on have also been translated to English, if anyone is interested I'll link the link to the blog of the guy who did them. The novels are much better, many things of 'mature' content got cut from the anime.