Pros
Good benefits and good pay. You'll meet a lot of smart people who want to do good work. They are protective of the legacy and with good reason--it's the only thing worth a darn.
Cons
The company has totally lost its way since 2014. They have no leadership with their technology and no direction/leadership within the company. If you watch Rackspace for over a year, you will see continual churn at the SVP and C-level because there is no driving vision for a road ahead. There is zero culture of accountability. People try big flashy programs and get promoted based on their initiative; meanwhile their initial programs are left to rot and fail. People chase their tails trying to find traction. If they are not successful within 4-6 months, they leave, only to be replaced by someone else with a new flashy program.