I know using computer programmes at home gets a lot of stick from parents who dont agree with it.
But, in some cases, depending on the child, it can work.
My own DS hasnt been on Whizz for a few weeks because she came across a lesson she found hard and didnt want to tackle it and kept stopping the tutorial half way through. (With Whizz you have to complete it to move on to the next topic). She went on it today and completed it straight away without any hesitation. Having had the introduction/lesson last time she used it, and having a break and going back to it, something clicked and she didnt struggle. It was quite interesting to observe.
In a class scenario, they would cover a topic, whether its for a day or a whole week, and then move on to the next topic, and not cover that same topic until a year later. If they dont get it first time, then they struggle next time.
With Whizz, they go over the same topics over and over again, just stepping up a level each time.
Criticism or not, I think it works.