As per the previous reviewer, I got this because I've only wooden floors and nothing to practise putting on. Its not too bad but does lose its challenge before too long. I've not played since I bought it so can't say if its made any difference.
For anyone considering buying it, it consists of the green mat glued to a vac-formed plastic section. The ball return is by gravity, so it doesn't actually roll all the way back to you as it would with a mechanical return. (On the upside there are no batteries!) The ball falls into the chute no matter whether you put it in the hole, the bunker or the lake. And if your shot is slightly too hard it will pass the hole by.
On my one, the mat was slightly misaligned so the ball always got caught in the chute. Some judicious trimming with a knife was required but its fine now.
Overall, fine for what it is. My kids love mine as well but I doubt it'll make any of us tour pro's. Its main value may well be in encouraging me to pick up the putter several evenings a week.