Been having issues with it.... with lots of over/under type results.
As I noticed a couple of recent reviewers have pointed out, you have to maintain full concentration with this one or it will be all over the place. ---HOWEVER...
I also have noticed that trying to be "careful" or slow down too much to get it to roll, didn't work for me either. Seems to almost need an aggressive delivery to go with it's nature. When I finally stopped trying to aim the thing, and just let it fly at a decent speed to a certain point on the lane and trusted it would come back, it did. Also... I tend to be a down and in type player, and this ball is pretty useless for that shape of trajectory.
It does help the rev-challenged players add some revs, but.... rev challenged players tend NOT to roll the ball toward the gutter and let it come back. Most, because of their low revs, I would think, are down and in style. So... ironically, if you buy this ball because you've heard or seen it help rev-challenged bowlers get some "stuff" on the ball.... you'll also need to learn to abandon your down and in style when using it, and swing it out somewhat.
Anyway... that's my opinion at this point.