I'm giving this one star.
Needs major work.
Can only do discounts related to subtotals.
No way to restrict it to only certain categories or products.
No "If customer buys this get this free or % off".
The module is almost worthless.
Doesn't even have a "spend X amount and get free shipping" option. These are some pretty basic features that nearly all cart systems offer.
I talked to xCart support about these features a couple years ago and they wanted me to pay them to build a custom module. These basic features should be included with the standard software.