It's a beautiful anime, the concept is great and it's executed nicely... But unfortunately it's lacking. It's supposed to be an anime that gets you emotional, that hits hard about the meaning of death and how to cope with losing a loved one, but this anime wasn't able to do so.
I can't pinpoint how it went wrong, but at the end of it we are left with an impression that this anime was wishy-washy. I noticed that they strongly focused on Mai (the couple's daughter) in order to avoid issues about the age gap between the couple, and that was a highlight of this anime, but on the other hand it made the Father merely a father and not a "husband". It made his character weak and unlikeable.
This is "mixed feelings" because I think that the story is worth it, but the anime isn't. So I would instead recommend watching the live action instead.