From a customer's, it means you have precisely zero assurance once you've paid that the other guy will follow through. It's just like sending cash through the mail, except with no chance it won't get there.
It is much easier build merchant rating services/databases than customer rating services/databases. Proof: compare (1) buying from a high-rated eBay seller which is pretty much riskless, to (2) the complex consumer credit rating industry which is doing a poor job at maintaining fraud at constant levels (fraud increasing year over year, small merchants going out of business, etc).
Therefore I assert that the Bitcoin model is superior: solving the fraud risk for merchants is more important than for customers. If a merchant start delivering poorly (or not at all) with purchases, he will quickly receive poor reviews and go out of business, hence self-correcting the fraud problem.
Of course another option with Bitcoin which you are not thinking about is to use escrow services as third party between buyers and sellers.
