I walked every inch of all the Warbler Vista trails on March 10th. Started just after sunrise and the only other folks there were the couple cleaning the bathrooms at the trailhead. They have just poured new concrete and asphalt road from 1431 to the first trailhead. Perfect road. And there is fresh mulch down on the trailheads and ends. The trails themselves are quite nice with great tree cover and some nice openings with views across the countryside. The noise from the nearby roads/highways was a bit of a nuisance but it was only occasional. I really liked the Ridge trail. It had a lot of rock and branch debris which made it a bit adventurous to get through it. Not at all a "nice, flat, improved" trail at all.
You'll enjoy these trails. Easy to get to from Austin.