Pros
Salary was within the range of other, similar positions in the area. Service discount was really nice - especially once I left and my monthly bill adjusted to a "regular" customer rate instead of an employee. I had some pretty amazing coworkers, peers, and managers over the years.
Cons
Post Sprint merger, the whole vibe of the company changed and not for the better. It became far less teamwork oriented and more of an us versus them feeling as round after round of layoffs came. Employees were reduced to numbers on spreadsheets that were expendable. Lots of quiet reorganizing that resulted in entire teams being let go in the same week as company social media touted "the best ever (fill in the blank) as if trying to drown out the flood of Linkedin posts from employees who were let go and now looking for work. The public facing persona did not match what was happening internally. T-Mobile lost focus on being the best cell phone provider and spread out into so many different directions that it was difficult to keep up as an employee and certainly difficult to maintain a consistent advertising focus.