One thing not really mentioned in this, or other similar discussions, is the personality of the person trying to learn. One person might learn more easily given the fast response time of digital, while another might respond best to the more studied pace of film.
In either case, however, not much learning is going to happen unless the student pays attention to details and has access to some decent guidance, either from a teacher, a book or an online tutorial.
For example, looking at a badly overexposed image on the back of a digital or in a strip of negatives won't teach anyone anything unless they already know the basics of aperture, etc., and recognize the overexposure for what it is. If they then adjust their exposure, get a good image, and link all that with an accurate memory of the conditions in which they are shooting, they might learn something they can apply the next time they shoot in similar conditions.
On the other hand, if they just start playing with the controls of a digital until the LCD produces something they like, they won't learn anything. Ditto for film, except they'll learn nothing more slowly.
If someone uses film, and if they can get it processed while their short-term memory is still fresh, the same kind of process goes on. Psychologically, film can inspire you to take more care with each shot. Doesn't have to, but it can. And, that might produce better, faster learning for some people.
However, you aren't going to learn much of anything if you put the camera on full automatic and click away. You'll likely get pretty good pictures most of the time, but that's about it. In that regard, it isn't so much an issue of film or digital, as it is an issue of taking control of the camera.
These days, anyone really serious about photographer ought to be conversant with both film and digital, and with manual and automatic cameras, regardless of personal preference. They're all in the toolkit.
