I used to us another cash back site but when I found that ShopAtHome offered a 110% price match guarantee with that site and others I was convinced that SAH was the best bet! I also touted this guarantee to many friends.
Alas, there is no more price matching. While I do still use SAH, I am careful to check other cash back sites to see who offers the best deal.
I have never had any problem with getting my money from SAH. Their customer service is a little slow to respond, but they do respond and I appreciate that.