Substantially, it's a bugs-fix X-Cart release which also contains small improvements and optimizations (for the full list of bugs fixed and improvements added please refer to CHANGELOG in the package).
However, we’ve also included several major improvements being intensively discussed by community:
1. PayPal Payments Advanced & Payflow Link iframe improvement.
Customers stay on checkout page and pay in pop-up iframe window.
2. Address book improvement
New fields can be added to Address Book