Has anyone taken a math course through Athabasca? My history with math is not entirely positive, and I'm slightly worried about having to teach myself, and not having a TA or Prof to talk to if I run into trouble. I understand the layout of Athabasca; but how challenging did you find the course? How were the tests?

I know Mac only sees pass or fail from Abathasca courses, but I've heard grad schools will pull your marks.

It depends how independent of a learner you are. There are some people who ask a million questions and require feedback at every step to confirm that they're doing things right, and then there are people who just figure stuff out on their own. If you're the former type of learner, then you won't do well in an online course.
There is still a TA that you can talk to but it's not face-to-face obviously.