I have used this parking area at least 15-20 times  and never experienced more than a 10min wait. The cost is significantly less than long-term parking "at" the airport and because it is soooo close it really doesn't take any time to shuttle over. The staff is friendly and they drop you off right at the door! I definitely recommend utilizing this parking area if traveling out of SAT, especially if you're parking for more than a few days.