Pluspunten
Open Source. Lots of good people. Plenty of room for growth. Lots of offices, so you can move where you like. In tech circles, there is a certain amount of sex appeal. I.e. for a large multinational IT corporate, Red Hat has a lot better rep than Microsoft. Great servers, good pay, and lots of perks.
Minpunten
While we're technically "open source", we're not really. The business model is, put out great software with crappy documentation, then sell services. For my money, if I were starting a business, I'd go CentOS. Mind you, Red Hat is a necessary evil. CentOS wouldn't exist if someone didn't pay Red Hat to continually improve their product. If you hear "open source" and think cutting edge and open, go somewhere else. Red Hat is a major corporation and it's run like one.