Only Yesterday (Omohide poro poro) is quite a mature anime aimed at the josei audience (females from late teenage years to later), according to Wikipedia. It has a very heartfelt story that isn't usually found in animated form, but Studio Ghibli adds its own touch of magic to it without straying from reality.
Unlike many other Ghibli films, this one isn't really for kids. It deals with more mature ideas that wouldn't necesarily be unsuitable for children, but they may not find it that interesting. Long periods of silence in the dialogue also highlight this, but for an older viewer it is a lovely piece of film.
A wonderful film from Ghibli, unlike much of their other films from both before and after. A definite watch for fans to see what the Studio is capable outside of fantasy.