1) The management. They have WAY too much management. I've worked in many multi-billion dollar companies before and I've never seen this many tiers between the employees and the CEO. To this day I couldn't tell you the leadership chain between myself and the CEO. If I recall, there were something like 47 Vice Presidents. It boggles the mind.
2) The insurance is terrible. I was hit with unexpected bills typically covered by insurance (every place I've worked before anyway). Two MRI's for about 3k and a boot for a broken foot were not covered. I didn't know they weren't covered until I received the bills. Not a very nice surprise.
3) Salaries are really, really low - even adjusted for the cost of living (and no state income tax).
4) If you're technical, and decide to leave (the San Antonio office), you will probably have to move. There aren't many decent paying technical jobs in San Antonio. Austin has quite a few, but it's not an easy commute. Rackspace has an Austin office. If you can choose, go to Austin.
5) They do have fun, but it comes with a prices. The place is a really, really loud environment. Some people may not mind, but it was really tiring for me.