This blogger's reaction to Google Apps as an LMS is essentially the same as my discussion thread entry when I discussed my preference of Google Apps over Moodle.
Another nice feature is that you can make as many assignments as you want and your students won’t see them. They won’t see them until you “Give” the assignment
I agree that Edmodo might be a little simpler to set up a single class, but of course that’s not scalable in a school with more than one class since the goal is to have a single account per student that allows them to access all their classes, not one account per class