Pros
There are some wonderful and very smart people to work with at T-Mobile. It's an exciting and fast-paced industry to learn and to work in. The pay and benefits are competitive and the vacation time is generous. There's an opportunity to meet and work with a variety of people, both at the headquarters in Bellevue and at other locatons, such as retail stores, call centers, and distribution centers. The company is owned outside of the US, which can be both good and bad, depending on the situation and economic climate. It provides a good large-company experience overall.
Cons
My experience was that I was very engaged and excited about my work and my role when I started in 2008. As the next couple years went by, I watched my role diminish to simple tasks; our team did not have a strategy and we became "short order cooks" to our internal customers and were very reactionary. I also watched many of my colleagues get laid off/have their roles eliminated or jump ship (as I did). Many were and are concerned about the stability of the organization and where it's headed. There were many reorganizations that greatly impacted people's productivity and ability to focus. I was lucky that I only had two managers in two years; some people I know had four in that timeframe. Yet, it was unclear what all of the re-orgs. accomplished and how they changed anything for the better. It's one thing to shuffle boxes on org. charts - it's another to actually change behavior. It's very much a "ready, shoot, aim" environment - only when something has launched/gone out the door with problems is there reflecttion; projects need to be set up for success from the outset. Professional development became non-existent due to either lack of budget or role eliminations/there being no place to move to.