The idea is good but it is still based on trust to unknown 3rd party.
How do you know the buyer is not conspiring with the arbitrator, wait for the delivery and subsequently leave with the BTCs?
Even if they implement a feedback system it will require trust.
1. Suppose that Alice wants to send money to Bob through escrow. To start off, Alice goes to the Bitrated website and goes to Browse arbitrators. She then selects an escrow agent (say, Trent) and clicks Start transaction.
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Finally, Trent himself has no opportunity to run away with the funds. In theory, Trent can conspire with Alice to split the funds fifty-fifty and leave Bob with nothing, but such a situation would require two of the three parties involved to be dishonest, rather than only one.
I think arbitrators should put down an amount of BTC and be limited to escrow for that amount.