Beautiful, contemplative, intense, and strange.
This series kind of spoiled me, and I've never found anything else quite like it. A mixture of mystery, fantasy, slice-of-life, and drama. Simple, but beautifully made. There's basically no action and no romance, but it's stuck with me more than almost any other anime. It gets much more dramatic and tense about halfway through, but you'll know after the first episode whether it's your bag or not.