Roughly 10 "challenging problems" each week, plus some Alcumus, plus some bits to read from the book. So far 8 of the problems are short-answer, automatically marked, and two are proofs for him to write which are marked (pickily!) by a human. The first few problems tend to be routine, but there have been several I haven't been able to do instantly - I've taken to looking at the challenge problems before DS does :-)
For us, whether it ends up feeling worthwhile will really depend on whether DS gets into talking to other students on the forum. He can't attend class in real time because of our timezone. It is pacing him and giving him an incentive to stick with a graded set of problems, which is good, but I could do that for him using the book.
I did wonder whether Intro to Geom might be a little easy for DS; I needn't have worried about that! One thing you could do in considering the algebra course is to get the book, and give him a selection of challenge problems from it to try. If he can do those readily, you might want to move up a level. But I can certainly speak to the fact that merely having done the material before is not a sure reason to dismiss an AoPS course.
