I have the opposite opinion of ALEKS. My son has to use it for precalc, and IMO, 3 correct problems is nowhere near enough to say that he's mastered a given topic. That said, the kids in his class aren't getting any instruction because their teacher has been out since early January, and ALEKS is being used as the primary vehicle for learning the subject.
I think that the larger problem with systems like ALEKS and the Khan Academy is that they don't teach the depth that's there in mathematics. Yes, they teach the basics, and the Khan Academy is good for explanations, but the depth just isn't there in the course sequences.
