Pros
The company leverages their abundance amount of resources to help employees be more successful. Management does a good job of investing time and energy to give everyone a fair opportunity to make money and be successful. Sales is a performance based job that your effort determines your income level. Those that can do the "whole job" and take care of customers properly will be successful and recognized/rewarded. Great benefits for craft employees and good benefits for management. Because AT&T has union backed employees, this creates issues that affect both sides in how the business should be run vs how it is dictated to run. Large, established company allows for growth in many areas and departments.
Cons
Union. This is a well established company that is old school in how employees are treated. They do not offer an environment that would be seen in start up and dot com type companies that allow a lot of play time during the day. You are expected to work. Some may view that as a negative.