"Ash" is an experience. It's the experience of death, of waiting for a parent to die, and of dealing with the whole process. It is, mercifully, free of any excess drama and angst: this isn't an angry, impassioned departure, but a restrained, understated passing. In a way, this actually makes the piece more "real", at least to me, and therefore more touching. Grief, for me, has always been more about the silent struggle than about wailing and rending of clothes; and then, of course, there's the reality of having to deal with logistics surrounding a final illness.
The story itself is pretty linear. In general, what choices we make tend to be immediate effects that don't affect the flow of the story. There are, I think, at least two exceptions to this: two choices whose results I see echoed further on. There might be others, more subtle in their effects, but I did not play through a second time to find them. However, I do not think that even these really change the way the story goes. One could be harsh and declare that the lack of real agency makes this less of an interactive experience, but I feel that the illusion of agency is quite sufficient. There's enough interactivity to put the player directly into the shoes of the protagonist, in a way that static fiction cannot.
And that's what it's about, I think. Putting the player in the protagonist's shoes; sharing the experience.
I feel that this is congee, with a few shreds of salted fish and green onions, and Chinese tea on the side. Some breakfasts are about a harmony of multiple flavours, but this is more about a single flavour drawn out and celebrated.