Pros
The Air Force is a great place for someone who doesn't know exactly what they want to do when they grow up. You'll be taught a skill that most likely will translate into the civilian world if you wish to carry it over. If not, than at worst you receive free schooling, great benefits, paid travel, you'll make some great friends, and it offers you time to grow and mature instead of heading straight to college right after high school. The jobs offered in the Air Force range from mundane office jobs all the way to spec ops, so there's options for just about anyone that qualifies to join.
Cons
I'm in the aircraft maintenance world so I'm speaking solely about that, I don't have any experience with any other careers. The politics in the maintenance realm are terrible. Everyone is so worried about their own career that most are willing to eat their own. It's easy to get stuck in one position if you show that you're worth while because leadership will tell you they can't afford to lose you, sounds like a compliment, but it's not. You just make their lives easier so they're willing to hinder your career to boost their own. The hours can be pretty long, I've worked more 12-15 hour shifts than I can remember. Overall I'd say it's been a lot of fun and offered a ton of great opportunities, but some of the issues with the politics will really start to wear on you if you're in long enough.