The merging of reality/memory is interesting, and the film largely avoids the usual anime tropes. This is not as out-there as other Kon films and is not adults-only, although it is a tearjerker. Some points are heavy-handed, as if Kon did not trust the viewer to get it. Well worth a watch.
(Saw a while back) In this film Kon's signature visual fluidity is in full effect. This time it allows him to move back and forth between the real life of an actress and the movies she made, and between the past and the present. By design, over the course of the film these become mixed and we start to look for visuals and scenes that echo and complement each other. Not surprisingly, the tone is quite somber.
Satoshi Kon takes you on a journey through memory in a manner that is not only deeply touching, but also fascinating and intriguing. It doesn't limit itself to the story of the titular character either, offering the sidelines to japanese culture throughout History.
This movie falls in the realm of Kon's more reality-bound pictures: fantasy isn't in the real world, but in any person's head, thus being 'real' in a different way. I strongly suggest to see Tony Zhou's "Satoshi Kon - Editing Space & Time" cinematography editorial video, to appreciate how Kon mastered editing and chose animation to avoid certain live-action limits.