Pros
There are great people here - my colleagues are some of the smartest and most passionate people I've ever worked with. They are at Red Hat for more than just a paycheck - they care about something bigger than themselves. The culture of transparency and collaboration is a refreshing change from "traditional" Fortune 500 companies. The opportunities are endless to do challenging, exciting, and valuable work. You don't have to take a traditional career path here. It's nice to work at a company where the collective energy is so positive.
Cons
Some aspects of the culture aren't scaling well with the rapid growth and it can be a bit chaotic. Despite a focus on collaboration, many people are surprisingly slow to let go of tribal knowledge and contribute to collective/shared knowledge and work. Not every department has the same feeling of collaboration or trust in their own people and/or other departments.