Given the premise, it's not exactly inappropriate, but I think this one maybe pushes its sentimentality just a little too far. The first scene – a normal hangout with the crisis of Gio's illness looming underneath – is fine conceptually, but the presentation never stops gesturing at the absence; the grayscale backgrounds are not subtle in how they evoke loss & nostalgia, and all the music is pretty heavy-handed. Something can also be said about how matter-of-factly the writing explains both the premise and a lot of other stuff, rarely if ever lingering in the ambiguity of what is happening or what the characters are feeling. It's just all a lot together, and the game doesn't really hit the emotional complexity it strives for.
That being said, it's not a bad first attempt at a VN at all, and most of the basic building blocks of the medium are tightly in place. While I had mixed feelings about how the backgrounds fit this particular story, doing something interesting with your stock images was a good impulse, and even if the style of the prose could be honed, it's functional and readable.