Why is this impressive? It's not made out of paper. I see plastic lenses, LEDs and batteries. I can buy a microscope on eBay for less than $2 (http://www.ebay.com/bhp/pocket-microscope). Why is it better for the housing to be made out of paper than plastic?
The pocket microscopes you linked to provide 60x magnification. Imaging of most microbial infections that can be diagnosed visually requires at least 1000x magnification.
The Foldscope project provides over 2000x magnification.
Also, the 50-cent cost is right now. They hope to get the cost down significantly lower by scaling up production.
Finally, it doesn't hurt that the Foldscope is significantly more rugged than a plastic microscope. You could easily stack a thousand of them in a small pack and bring them to some remote region on foot, horse, or motorcycle.
Here's my 2 cent microscope "made out of water": http://citizenscientistsleague.com/2013/08/29/the-instant-mi...