I enjoyed this. I saw the ending coming long before it came, but I didn't think the story depended too heavily on that being a surprise.
I don't think that I would use the box, at least in my current state of mind, but in a moment of deep grief I can understand why you might want to do it. Am thinking of grieving of a loved one. At the same time, since the box can't actually bring back a loved one, your choices would be to remove the memory of the death, leaving you with confusing lack of closure, or to remove memory of the person entirely, so that wouldn't be great usage anyway.
At the beginning of the story I thought he was an extreme odd character because of his complete inability to cope with anything unpleasant, but as the story went on I understood that this was a direct consequence of the Box being there--a slippery slope that he's gotten rid of an argument here, a traffic accident there, and keeps escalating until he just can't handle anything without the Box. It would be best if he erased his memory of the Box and left it somewhere.
But I can think of better uses for the box. Imagine being able to go back and read your favorite book for the first time, again. See your favorite movie for the first time, again. That was the use I came up with, and I prefer to think that I would use it for something like that instead of getting rid of memories that cause me pain.
Again with Eternal Sunshine of the Spotless Mind, this quote did come to mind:
Joel: Is there any risk of brain damage?
Doctor: Well, technically speaking, the operation is brain damage
No matter that how magical vs. sciencey the Box is, I'd still consider it brain damage. I can't believe there aren't long term neurological consequences to destroying memories like that, even discounting the obvious behaviorial problems that are shown in this story.
So many experiences are based on who we were at the time; I can that imagine seeing a film that I adored as a child (and re-watch as an adult with affection and nostalgia for memories of the kid I was when I first saw it) wouldn't be the same without memories of the first time I saw it. Sorry, that's a very awkward way of putting it - like, sometimes nostalgia is a big part of what makes us enjoy things, and if we see things through a new adult perspective, without that cushion of good memories, we mightn't enjoy them as much.
I totally get that, as I suspect that anyone who has looked up their favorite childhood cartoons on Youtube can. As I was growing up into high school and college I lamented that all the modern cartoons all suck. And while that was generally true, they didn't suck MORE than 80s cartoons, it's just that my perspective changed and now I'm left with nostalgiac inaccurate memories of those cartoons that I don't want to ruin by watching the actual shows again.
However, I do have to say that it works better in audio, where tone and delivery can make some of the lines - particularly Kim's dialogue - sound less off-the-wall. I have to agree that Kim was the weak point; the protagonist is messed-up enough that it's not jarring when he phrases something weirdly or makes abrupt leaps of logic in disregard of conversational flow, but Kim is supposed to be a normal woman; her fixation and sudden swerves feel out of place.
Who says Kim is supposed to be a normal woman?