Yes, my 4th grader did it this year. It's completely different from regular class - the math is puzzle math (for example, look at the types of problem here:
https://contest.rsmfoundation.org/StudentPortal/oly/welcome
The homework is also different, it's about 5-10 problems and at least for our kid, takes so much less time. We dropped the regular class though, but I wish we could have kept it. The cost is about the same, compt. class is a little higher, I think $300. he absolutely loves it and we will be continuing with it for next year.