Pros
General Air Force Pros: You get paid to train. Career progression is virtually guaranteed to a point. There is potential for travel to interesting places. Overall, a good place to start if you don't have any strong employment prospects or education. As for the job specifically: Aircraft maintenance is good, hands-on work if you like that. Generally, you'll work outside, if you like that. I do. The job can provide interesting technical challenges at times.
Cons
General Air Force Cons: As with any branch, you lose a great deal of personal liberty. You have very little influence on where you end up living. No matter what job you signed up for, you can get re-assigned to a job you don't want. You're likely to deploy fairly frequently. The leave policy is generous, if you can get your leave approved for when you want it, which is uncommon. Your career trajectory is rather fixed, particularly since you can't leave under penalty of law. Job specifics: Long hours, fewer off days than other jobs. The culture is still somewhat toxic towards women. It has gotten better since I've been in, but there is still progress to be made. There is a tendency to shuffle bad troops from job to job, rather than addressing the problem.