Why University of Phoenix has such a bad rep, I have no clue. I took several online grad classes there. They were, by far, the hardest classes I ever took, and I learned so much.
Just in case anyone is wondering, the other schools I have attended aren't necessarily "slouch" schools either. My undergrad is from Temple University. I've taken grad classes at Rutgers, Univ. of Massachusetts, & Drexel. NONE of them demanded as much from me as the 3 classes I took at Univ. of Phoenix did.