This one I liked a lot. Sure, it's not exactly a new or particularly shocking idea, but like Unblinking said, it portrayed a non-human perspective with unsettling accuracy. (Well, I say "accuracy" like I know what one would sound like, but you know what I mean.) I enjoyed the effort to spice up the reading, but like many such efforts, all it did was render me unable to hear what the bleep was being said while the SFX were going. (I have rubbish hearing and I tend to listen while doing chores like washing the dishes, so any added background hiss or white noise is basically turning on Scattercat Mute.) I did figure it out by the end, at least enough to appreciate the cyclical structure.
The main criticism I would have for this one is that I don't feel any more particular horror about the final Mary than about any of the others; it felt like the story just iterated its pattern a few times and then paused without really resolving much of anything. That's not even necessarily a problem, but it made me wonder a little why she got so much more build-up than the other victims.