We have been using Maths Whizz for just over a month now having previously used Educationcity. I'll share my thoughts...
I have twin boys - summer born in Year 2 - both similar average ability.
When you subscribe to Maths Whizz your child does an online assessment which gives you a Maths Whizz Maths Age - the starting point for exercises. Maths Whizz make an ambitious claim to improve your child's Maths Age by 2 years in 12months as long as your child uses it for 90mins every week.
Thing is IME Maths Whizz assessments under report your child's Math's Ability - so both my kids scored a Maths age just above their real age. Sounds OK till I realised that all they have been tested on is Year 1 material and not even the whole year's worth. They are pretty confident with Year 2 work but the assessment somehow didn't get that far.
Consequently my kids have managed to improve their Math's age by a year in one month - miracle? and are predicted to have a Math's age of 16 by the end of the year
So I would take their success statistics with a big bucket of salt!
On the plus side my kids really enjoy using it - they enjoy earning credits to "buy" items for their online bedroom. The revision of a year's curriculum hasn't done them any harm - probably has added to the enjoyment by consolidating their knowledge and building confidence because they can more easily earn credits but I don't know how much they will enjoy it when the Maths becomes unfamiliar and the real learning takes place.
I also like the gradual build up of difficulty and the tutoring element of the program - educationcity relied on one level for each year group and lacked any teaching element - so the challenge was too great at the beginning of the academic year and too small at the end.