Drupal Commerce was written from scratch, designed from the ground up by people who learned from the flaws of Ubercart, with years of ecommerce experience under their belt. It uses the new APIs of Drupal 7, which results in a significantly greater compatibility with contrib modules. This in turn results less custom code required for a new site, both theme and modules.
Benefits:
Paypal WPP
The primary advantage of WPP over WPS is that your customer stays on your website throughout the payment process. It offers a more professional user experience than being diverted to a Paypal page. From the customer's point of view, it is as if you have a full merchant account.
