Pros
Provided you put in your time, and continue to deliver, you can have a great deal of flexibility in your work/life balance If you work in San Antonio, you're in the mothership and will have nearly every resource available to you
Cons
Management can be hit or miss. This is not the place to be a new manager as you won't receive much in the way of help or empowerment. If you're in sales, your comp plan will be difficult to understand, track, and get paid on. It will also change at Rackspace's discretion. You can make money, but its a lot more luck than skill. The HR team is filled with nice people who are ultimately powerless to help you If you live/work in Austin, you need to be VERY clear during the interview about where you'll be working. Many Austin based Rackers end up riding the shuttle to San Antonio several times per week. Long story short - the first few years are really great, but once you hit 3 or 4, go ahead and start looking for your next adventure.