I'm in a test market as well and I'm liking it. I got the update almost a month before the official live date, and I'm almost up to 10k points, due to groceries mostly.
We have "cartwheel ambassadors" that are on the floor talking to everyone and trying to get them signed up for it now. Not sure how long that will last, but its pretty nice. If nothing else, they are the first responders for back ups, since they are in the front ends workcenter.
Overall, I think its a good addition and an easy sell. Get the folks signing up to list our store as their home store and bam. We get credit for it on some metric somewhere.