Are you moving here for work, school, family, or other? Have you gotten the chance to visit?
Moved here June 2007... love it. You're moving at an awesome time of year-- the summer weather in Saint Louis is simply amazing. And the fall is nothing like you'll see in Texas (well, ast least the changing of leaves is like nothing I have ever seen throughout Texas). However, it gets pretty damn cold here in the winter (and this last one was pretty bad).
One of the main reasons I moved here was that, upon reading up and visiting, the city struck me as a very outdoorsy place. When I was just driving around on my visit, there were people all over just walking, running, cycling, walking their dogs, practicing softball, etc. And, it also seemed as if at every few stop signs, I came upon another city park-- so with a CS comparison, anywhere from the size of the Polo Field to Research Park. There are a number of outdoors advocacy and conservation groups here. And, Missouri has a great state parks system (although not nearly as great as that of Texas), with plenty of regular annual fishing, hiking, birdwatching, etc. events.
Although we don't have an NBA team, pro sports are pretty big here... whether or not we're winning.

College sports (local) leave something to be desired... but, hey, at least you won't have to fight huge crowds.