Pros
If you come from a small company, Red Hat offers things like Employee Stock Purchase Programs, 401K matching and a variety of healthcare options. Your work life balance is exceptional and really good if you have kids and want to work a basic 9-5 job. You'll get 15 PTO days and the week between Christmas and New Years off without having to use PTO. Majority of the people are very nice and genuine.
Cons
Red Hat calls themselves a startup but are far removed from the scene with 25 years of Dot-com experience. You'll often be tasked with using programs that are long deemed as archaic. My department alone used 30+ programs to be what they considered "functional." Some of these programs were last updated in the 90's and were not considered to be obsolete. You have no say in trying to offer opinions on how to improve processes but will be put in groups where you waste your time weekly on coming up with ideas of how to improve processes without the ability to make a real difference. The majority of employees at Red hat have never worked another job and are unaware the opportunities out there for them elsewhere. This encourages group think and a lack of innovation since few people have an outside perspective. As a manager, if I had someone apply to work with me and I see they previously worked at Red Hat for more than a year, I would not even consider looking at them knowing how little them likely grew while working there. Business outlook is always questionable. Ask anyone who works there what direction they see Red Hat heading, most will have no idea. The majority of the company runs on the belief everything is going fine(who knows why) so it should continue that way. If you're looking for a company who tasks risks that create payoffs, this is not the company for you. If you've been acquired by Red Hat, start job searching asap.