My kids do it here in South Africa! We only started in August this year but my kids are absolutely loving it. More so because they have one-on-one lessons with a teacher who lets them skip stuff once they have mastered the concepts and who finds joy in the way they figure out additional manipulations and patterns.
We love it - and it's a growing craze here too with schools etc.
It's actually a core part of our home schooling right now - we only use Abacus maths (SEMAS is the name of the franchise here) and then Dreambox.com for online maths learning. I have put away all other maths books for the next few years in a bid to encourage fun and strong mental maths abilities.
