Ventajas
I have almost exclusively glowing praise for working at Rackspace. Training - There's a "Rackspace University" training program which will help to get you certified in a variety of IT certifications. All certifications are reimbursed. Training materials are also reimbursed. I obtained a RHCE, CCNA and Security+. Management lets you pursue what training you desire to take. Benefits - Humana, flex card, HSA, dental, vision, a rather generous 6% matched 1-to-1 401k plan, stock purchase, free physical therapy on site if at Texas locations. Quarterly profit sharing bonus. Real management - There's a lot less management BS, Rackspace's hiring process tends to pick top-notch people and there's less pointy haired bosses and a lot more constructive management. I felt engaged in what I was doing and motivated to do more. I've never worked at a company where I felt so actively involved and satisfied with my work. Name Recognition - Having worked for Rackspace is a bright shiny gold star on your resume.
Desventajas
The primary con was the salary offering, which is average at best. I would still be at Rackspace if I hadn't received an offer that Rackspace could not compete with. I wasn't even job hunting, they found me. The secondary con is based upon the primary con, there's enough attrition happening because of better salary offers elsewhere, it's difficult to maintain teams with high levels of training and sometimes I would be doing the workload of several employees.