The best place to ask about the quality of any extended warranty is the shops who do service work that is paid for by them. If the shop manager says it is a good one, that means that it not only covers most problems, but it also says that the company pays the service provider promptly and without excessive paperwork. There are contracts around that some shops will not accept for payment because of problems in getting paid.
I suggest that you may find it helpful to read this article from Escapee's Magazine
on extended warranties, before you spend any money on one.