Katy has wonderful schools and the crime rate is really low. It has a small town feel, but it's not so small that everyone knows everyone. It's close enough to Houston to enjoy everything the city has to offer. Texas Children's and Methodist have recently opened new hospitals in the area.
Katy has plenty of good restaurants and the nightlife is picking up. There are a few bars with live music and a couple of clubs. The Houston area was not as severely affected by the recession as the rest of the country, but houses are still cheaper than they have been in a long time. The cost of living is VERY low and there is no shortage of available housing.