Pros
This is an institution, and any way you slice it, there's some weight behind telling people you work at AP. And of course, they're not going anywhere anytime soon. You're always on the forefront of the news, and it's an exciting place to work, depending on your department. The benefits are comprehensive, and depending on your department, the pay can be more than competitive.
Cons
Unfortunately, as a business, AP is horrible. There are way too many managers and not enough "workers", and no incentive for change--people work here for life and have no interest in rocking the boat when you can just keep your head down and work until retirement. For anyone with plans to make change, be progressive, or grow their career beyond AP, it'll be very hard to come up with any impressive bullet points for your resume. Technology is about 3 years behind everyone else, in almost every aspect. Everything is basically as though your 70 year old uncle would do it. The corporate card is Diner's Club, for Pete's sake! HR policies are borderline intrusive (you have to submit to a blood cholesterol test, body weight/dimension measurement among other things, or else pay a $300 fee for the right to keep your health information private, for example), and there's a distinct difference in the way the administrative workers (aka anyone but the "journalists") are treated, because they're not protected by unions the way the journalist employees are.