While in Austin, I took a short visit here. Panoramic views and cliffyness abound. However, while it claims to be the highest point in Austin, you can see several hills in the immediate vicinity that are obviously higher! I want my money back Austin. Also, your lake is just a dammed river. Shame on you.
I visited Mount Bonnell several times circa 1999-2000 when I lived in Austin. Visiting my company's Austin offices last week, I decided to visit again and thought: Wow, this is a great urban overlook! It was hotter than Hades, I thought I was going to die of heat stroke, but the sun making the limestone glow orange, the neat views of the downtown skyline, the gentle Hill Country scenery to the north...definitely worth the short walk.