Amazon's customer service (for the web store at least) is fantastic.

Even if the core shopping/delivery service fails you, if you complain, they'll take the "customer is always right" position and make you whole. They'll refund or re-ship with no questions asked, without requiring you sending back anything or even so much as providing proof.

I'm sure some people must take advantage of that level of customer service, but it's a really pleasant experience.