We have something similar here; it's called InTouch. I can log in and see her grades, discipline (she got one for not having her ID!! I never would have known!), health info, etc. As a parent, it's great and I love it.
As a teacher, there are always parents who call you weekly to ask why such and such a grade isn't in there, or why there haven't been grades since whatever time, etc, and it's really annoying. I don't know how the one in Austin works, but if I update my gradebook online, it doesn't automatically "roll over" to be updated in InTouch. That is done by the district at certain times.
But other than a few parents who go crazy over every little thing and who think you are spending 24/7 updating their kids' grades, I've really liked the online system.