Pros
Best of the best in the managed hosting industry. Rackspace is a company that in the last 10 years has achieved what it has taken many other companies significantly longer to do and is still continuing stong even in the face of a very tough economy. Because of how fast the company is growing there are always opportunities to be had and much you can learn. The companies main goal is support for its customers and will often to anything possible to make the customer happy which is nice to see, but will spoil you in your own efforts to seek good customer service elsewhere.
Cons
It really depends on the department. Rackspace has done a good job of saving money by being tight in certain areas which unfortunately keep us from having some benefits that should be "standard" in todays job industry. No matching 401(k), no tuition reimbursement, NO QUOTA RELIEF FOR SALES REPS WHO WANT TO TAKE A VACATION. Sales at Rackspace is very tough. Sales anywhere is generally tough, but not like it is here. You are often given little to work with and are held to insanely high quotas. Commissions are weak to say the least and you are simply a number. Perform or get out. It has been over 4 years since I've been able to take a vacation because you cannot get quota relief, so if you decide to get away for a little while you end up shooting yourself in the foot.