I didn't say it won't work. It's just that the seller doesn't care to put up enough information about how to use this hardware like the original designer or someone distributing it would do. If I am not mistaken, Lady Ada(adafruit.com) designed her original arduino protoshield, which is sold at several places. The design is in public domain so anyone can make them and sell. You get what you pay for, maybe not so much different on hardware, but pretty obvious on support and documentation, examples etc.
Anyway, if the sparkfun shield is the same (compare pictures), just use the sparkfun documentation. You'll be just fine
Here is adafruit protoshield tutorial:http://www.ladyada.net/make/pshield/
Open-source hardware is a dream world for copy cats and knock-offs. They make money while someone else is making the design and supporting users, or even taking blames ]
The ebay seller simply copied the texts from sparkfun website word for word:http://www.sparkfun.com/products/7914