This is by far my favorite hike in Austin. I can legally have my dogs off-leash and it's a great length, takes me just about an hour. It's hard to visit when the creek starts to dry up. I don't want my dogs wading in and drinking stagnant water. But when the water is flowing, I'd be hard pressed to find another hike like this and I'm here at least once per week. It's a great work out, for both me and the pups.
I highly recommend getting here ridiculously early on the weekends to beat the crowd or going during the week if you can. I really dislike hiking when there are lots of other people around. (Not that I don't like people, it's just that hiking is my alone time.) I get there around 6:45am and just see a few other die-hard, friendly folks who are there for the same reason... to get some exercise, be surrounded by the stillness of nature, and spend time with their dogs.