I would like to know if there are many retailers out there using this feature, do you have experience with it yourself if so how stable is it, are magento / adobe keeping up support for it and extending it going forward?
I am not sure how do you intend to quantify if there 'are many retailers out there using this feature' :) I guess it all depends on the type of business and the experience of the person you are asking.
I worked with this feature in M1 and everything was OK, was able to extend it and add custom actions that the customers got rewarded for and so on. I didn't use it yet in M2, but I don't expect a different behavior than in M1, the flow looks the same.
Since this is a feature for Commerce edition only, I can only assume that yes, Magento / Adobe will be keeping the support for it. If it didn't go away when moving from M1 to M2, I am pretty sure it is here to stay :)