I decided to give them a try a few months back, and they did a great job of taking care of my passengers. Rental car was pulled up to the plane, and everyone was friendly. Unfortunately the pilot areas aren't quite as nice, and there's no crew car (although they will drive you somewhere if you'd like). I don't think there was wireless internet there either.
If you're only going to be there for an hour or two, I'd say they're fine. But if you're going to be there all day, take the plane to Million Air, Piedmont, or Ratheon.
We were just in SAT Saturday night. We used Million Air because they were the better priced COLT fuel dealer on the field. Nice FBO, clean, modern, and friendly service, etc.
If overnight and it is your first time there, I would suggest staying down by the River Walk. A lot of fun and Million Air will take you to your hotel there. Some of the other FBO's will not drive you that far.
Nayak is kind of a ghetto FBO as far as facilities are concerned. My dad flight instructed there in the 60s and 70s to give you an idea of the age of the facility. Also a much longer taxi to the usual active, although there's never any delay there. There are two Piedmonts--Peidmont south is the one by the tower that everyone uses. Pretty nice inside. Raytheon has good line service and facilities are ok. Raytheon just instituted a "min. fuel purchase or pay the ramp fee" program, but the minimums are so little, they're laughable. Just trying to get folks to buy a little courtesy fuel, I suppose. I'm at SAT quite a bit and originally from there, so I'll be glad to answer ?s on places to go etc. My .02.
Thanks for the input. I think we will just go to Million Air (been there before and good pilot facilities) Just there for the day but would like to get back to the river walk had some good times when I was stationed there.