Yeah, the methodology is unorthodox, and I had my doubts at first as well, but it's cheap, so I figured I might as well try it. What I've found is that it makes an excellent cup of coffee (though I do tend to brew a little hotter than they recommend), but it uses more beans/cup than most makers would. That's fine for me, as I live alone and it's an excellent one cup solution, and still more efficient than brewing too much and throwing some away. While it claims to be able to make up to four cups at a time, I don't really like the brew for more than one, as in order to use enough grounds, it's difficult to fit enough water.
In fact, I have two of them, so that when my girlfriend stays over, we can brew two cups separately. This definitely results in better coffee than brewing two cups at once in one Aeropress.
As far as the short brew time, they claim it's the pressure that allows it to work. I'm neither an engineer nor a true coffee expert, but I've tried most of the ways that are supposed to allow you to brew a small amount of good, strong coffee, and the coffee coming out of the Aeropress tastes good to me.