Pros
This part really depends on your age and your previous work experience. The atmosphere here is pretty laid back. The offices are geared towards openness and fun, meaning there are no 'offices', only cubicles, mostly with low walls between so you can see over them. Fun in that there are things like funky themed meeting rooms, slides from one floor to the other, video game machines, etc., to keep the employees entertained. As far as benefits, Rackspace has very nice ones. They've finally got a very good, competitive health care provider with a nice array of options. There's an ESSP and stock options program. And I find that the PTO program is very competitive. I've been here almost 8 years and I get 6 1/2 weeks off a year.
Cons
The thing I most dislike about Rackspace is the management structure. I've personally seen over 20 people promoted to management that should never in anyone's wildest dreams be managing anything, much less people. You can get promoted here based on who you know more than what you can do or what your experience is. That drives me crazy. Also, too many people are still hanging on to the 'startup' mentality, even though there are now over 6000 employees here working in mutliple countries. The days of just winging it should be long over. Unfortunately, too many people, a lot of them the exact managers I'm complaining about, just do things based on whatever sounds good to them. If you're looking for things like agile, look elsewhere. Project management here is a joke.