Pretty neat. There's an amusing sort of bluntness to any sort of discussion of violence, murder, et cetera, that often gets seen in "black comedy" and the like. The intersection between very serious and "I can't believe this is happening right now!" that always lies within painful realities. This story hits exactly that point. It's a form of existence quite well suited to the monologue; after all, the reader has no power to actually affect the culprit except progressing or denying the story, so we are, in many ways, chained to the floor without mouth or limb. Ironically, every story is more or less like this, fictional entities speaking to us in an almost perverse sense, rambling to our prone form while we sit here taking it.
This story isn't exactly funny - but it's funny that the culprit chats in such an almost matter of fact way with us - the comedy of awkwardness, I suppose. After all, a grizzled predator wouldn't even think twice, or perhaps would only act so as to enjoy manipulation of the prey's feelings. In fact, for all we know this is, in universe, a play - a person who has killed a great many times putting on a show just for the amusement of watching someone squirm and writhe in the hopes that they may still be freed. Murderers often enjoy the glimpse of freedom in someone's eyes, some enjoy total submission, others the crushing of hope, which requires some in the first place. It's quite difficult to tell, isn't it?
The ending is open-ended, but is it really? It's exciting, right?