The park is very nice...a good place to try your hand at bouldering (where most of the crowd hangs out, across the dam from the entrance).
My favorite feature is the very nice hiking trail that starts from the west side of the lake and traverses the old Fort Wolters maneuver area (WWII and VietNam-era post). There is a nice primitive campsite not far from the bluff line on the north end of the park. I believe you need to carry all the water you need; there is a creek that flows through the area, but I'm not sure where it is in relation to the campsite. It's been ahwile. Anyway, if you use that water source, you will need to treat it or use a decent filter. Best to carry water, if you're just doing an overnight trip.
Here is the link to the State Park website. Lot of good info, to include trailmaps.