Keith Zars has probably built more pools in San Antonio than any other company, but they use a standard kidney bean shaped form for nearly ALL their pools. We live near Bergheim TX and have a neighbor with a new Zars pool. The end product looks ok, and I have not heard of any trouble since the completion. (ALL pools construction companies seem to have bumps while building, the good one's will work things out until you are happy.)
Just my opinion, but the Zars pools all look basically the same except the colors chosen for finishes. To me they were un-inspiring, a bit too "Wal-Mart". We wanted more "wow" - especially when you consider how much pools cost.
We had a pool built this spring ('08) and went with River Oaks. Overall we LOVE the completed pool! It's totally custom 23k gal - only one like it on earth and it's got a big "wow" factor. We learned that San Antonio pool companies mostly use the same contractors for concrete, gunite, rock work, etc. Talented contractors cost more, not so talented ones are less. This rolls into the price of the pool - you get the idea. I encourage you to shop around, ask to see the completed pools and talk to the owners. Good companies will drive you around and show you several they did and introduce you to the owners. If you check out River Oaks, they have a designer there that is very talented named Chris - ask for him.