We found mathletics really useful for introducing concepts to my DD, whose LDs make it really hard to learn brand new concepts in class, also it was just enough drill for confidence building for her. But it was way less complex and rigorous than the way the same content was covered at school - usually only one way of asking the same sort of question for example, making it super easy for the child to predict what the required calculation was, while teachers might phrase the question many different ways to make sure the kids know all of those ways of asking require the same concept, and likewise that there are multiple possible ways to solve.
My DD completed her year level in 10 weeks or less, she was in remedial math at the time (not PG at math!), its just really quick and easy to rip through, it helped her get out of remedial math, but primarily through making it easier to understand class enough to follow all the other stuff they covered (she has CAPD and has almost no chance of following completely new concepts given verbally in a group setting).
