This is another great tutorial, and as you said, one that's critical.
I particularly like the first section with the exposure triangle: it's very clean. I can see the points people have made about how things are described.
Since the tutorial describes things in terms of "sensor" throughout, perhaps it would make sense to just put a note early on saying that film behaves essentially the same, but the ISO is fixed when you load the camera (except it can be pushed around some in the darkroom).
If I can be so bold as to pull together some of the comments, and suggest perhaps:
Aperture: determines the size of the opening the light has to reach the sensor; intuitively, the quantity of lightIn the shutter speed section, would it be worth explicitly calling out camera shake? You mention hand-held and tripod, so it's basically there. Maybe it would just add to the confusion, because 1/focal length has gotten so complicated with sensor sizes and image stabilization. But even without the rule of thumb, it would explain why the "camera shake" indicator keeps coming on (or they get blur) in "landscape" mode when it's a little dim, but not in "night" or "portrait" mode, which I think would be very helpful to people.
Shutter speed: determines the duration that light is permitted to act on the sensor
ISO speed: determines the sensitivity of the sensor to a given quantity and duration of light
In the ISO section, instead of, or in addition to, the shots of gray, would it be good to have shots of a low-light scene? It might be useful to see that the noise is most noticeable in low-contrast areas.
I'm creating more work, too, I'm afraid.