Pros
AT&T is competitive in pay, and there are many opportunities to move around and up in the company. There are lots of opportunities in growing arenas such as Internet of Things cloud services, big data, etc. There's a ton of technical and career education available free to employees. The tuition reimbursement plan is excellent. For example, you can get the entire cost of a Udacity nanodegree paid for. Also, you could get the online masters in CS at Georgia Tech paid for, and being an AT&T employee might even help you get admitted into this very competitive program.
Cons
All of the stereotypical downsides you expect from an old-school Fortune 10 company are there in spades. Particularly, I'm thinking about the demoralizing and stultifying bureaucracy and administrative red tape. Reorganizations feel frequent and arbitrary. In the past year, there have been many forced relocations to Dallas (and to a lesser degree, to some hub locations in New Jersey, Atlanta, Chicago. The homogenization of wireline groups and business practices onto mobility have been very frustrating for many.
