This is a smart strategic move by Google as it is an advertiser incentive and retention strategy first and foremost. The added “discount noise” will make it harder to compare ROI rates to Yahoo! Search Marketing and MSN Adcenter. Judging by the number of vendors that signed up, they put in a lot of effort to launch this.
But make no mistake, after control of the delivery channel, this is ultimately about control of customer data. And in that regard, I’m not sure the customer value proposition of one account alone is enough for people to make this change. Having one checkout account is nice, but I’m not sure that will be significant incentive alone from customer’s point of view. The consumer already has checkout and/or fraud protection. However, the merchants save by having the payment go through there if they are an Adwords advertiser, so they may eventually provide incentives to do this.
What will be most interesting is to see how and if this service evolves with new features in the future.