Generic sound deadener

Anyone use generic sound deadener/insulator on doors & floorpan? Would like some feedback on your experiences if so. Here is a link to an ebay auction I've been contemplating. Need unbiased opinions. Thx

http://cgi.ebay.com/50-Sq-Ft-Sound-...954?pt=LH_DefaultDomain_0&hash=item4156841cda