Hey, I finally checked this out this morning with my son, and I liked it. I am confused by a lot of these sites, but this one seemed easy and totally worth $20... plus if they'll track what he's doing, great! I'm actually pretty excited because I've been at such a loss about how to motivate him.
I had him do the demo lessons this morning... he did grade 2/3 math (which he said was too easy, but there was no computation, which is what slows him down) and put him on grades 4/5 for science and language stuff... he did all those demos while I was showering and putting baby down for a nap, then he moved on and did all the grade 6-8 demos as well. He loved it!
For years I have been struggling to keep him off the computer completely, thinking it would be like poison to him or something.