Pros
Incredible scope to seize opportunities, grow with new and emerging projects. Open source is amazing. A lot of the people are great, super smart and committed. I had an amazing tenure here, but got out when the politics started getting to me.
Cons
Company is full of turds: underqualified hacks who have been with the company for over 10 years and promoted way above their capabilities, and recent refugees from big companies like Microsoft, Oracle, EMC who Red Hat thought they needed to legitimize themselves as they grew bigger but are just a bunch of dead weight. Political infighting like you wouldn't believe. If you can avoid the land mines, the toxic people, and the zombie projects you can get things done, but it's not the company it was three years ago.