Hi,
The casting quality looks good. Prices seem to be 1/2 of Dwarven Forge (unpainted). The material must be different, as it can chip, and that would be very hard to do with the Dwarven Forge material.
Since the material is porous and unpainted, you would want to put on a protective coat, or go all in and put on a proper paint job. The guide from Dwarven Forge should probably work,
http://www.dwarvenforge.com/city-builder-painting-guides/, as should the guide from Hirst Arts:
http://www.hirstarts.com/painting/painting1.html. You will be able to find other painting guides with a bit of searching. Since the material is highly textured, basic techniques -- overall coat, plus washes and dry brushing -- should work very well.
There are some very inexpensive sets, e.g., this crypt for $20:
http://www.dungeonstone.com/zen/index.php?main_page=product_info&cPath=7&products_id=4. I'd recommend getting one of these and getting a first hand feel for the pieces.
What I can't say, and will be important, are the weight and toughness of the casting material. With larger sets, weight becomes important, since there is the burden of lugging the pieces around. For toughness, there is a huge range, one the low end with plaster, and at the high end material which is essentially dental cement. According to the FAQ: "Answer: We make our models from a resin and carbon infused, diestone composite material which has a compression strength of over 17,000 pounds per square inch which makes them very solid and suitable for literally years of use." But I'm thinking tensile strength is more important, so I'm not sure how to take that answer.
Thx!
TomB